743
FXUS61 KCAR 031551
AFDCAR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
1151 AM EDT MON AUG 3 2020
SYNOPSIS
LOW PRESSURE WILL TRACK NORTHWEST OF THE REGION TODAY. A COLD
FRONT WILL CROSS THE AREA TONIGHT. ISAIAS WILL TRACK NORTHEAST
ACROSS MAINE WEDNESDAY. AN UPPER LOW WILL TRACK NORTH OF THE
REGION THURSDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION
FRIDAY.
NEAR TERM /THROUGH TUESDAY/
UPDATE...
A TROPICAL STORM WATCH HAS BEEN ISSUED FOR ALL OF NORTHERN AND
EASTERN MAINE WITH THIS UPDATE.
PREVIOUS DISCUSSION...
THE NAM AND GFS SOUNDINGS SHOW SB CAPE JUMPING TO 1000+ JOULES
W/35+ KTS OF SHEAR. SO, CONVECTION IS POSSIBLE. THE CAVEATS ARE
THAT THE DEPTH OF THE MOISTURE DECREASES INTO THE AFTERNOON
ESPECIALLY ABOVE 800 MBS AND MID LEVEL LAPSE RATES ARE NOT THAT
STEEP. THE LLVL LAPSE RATES ARE FORECAST TO STEEPEN INTO THE
AFTERNOON TO 8.0 C/KM WHICH COULD BE ENOUGH TO ALLOW FOR SOME
TSTM DEVELOPMENT. THE 00Z NAMNEST SHOWED A LINE OF SHOWERS/TSTMS
SETTING UP ALONG THE PRE-FRONTAL TROF W/THE SOUNDINGS SHOWING
POTENTIAL FOR A FEW STRONG TO MARGINALLY SEVERE ACROSS NRN AND
ERN AREAS. THE NAM APPEARED TO BE OVERDOING ITS MOISTURE
PROFILE. THE LATEST HRRR HAS BACKED OFF THE ORGANIZED CONVECTION
AS DID THE RAP. PWS ARE EXPECTED TO BE 1.5+ INCHES W/THE
POTENTIAL FOR BRIEF HEAVY DOWNPOURS. SOME STRONG WIND GUSTS ARE
POSSIBLE IN ANY STRONGER CELL. CONFIDENCE IS NOT HIGH ENOUGH
ATTM TO INCLUDE ENHANCED WORDING IN THE FORECAST.
THIS ACTIVITY WILL BE PULLING OUT TO THE EAST BY EARLY EVENING
W/THE COLD FRONT SLIDING ACROSS THE REGION. EXPECTING SOME
CLEARING AND COOLER TEMPS BEHIND THIS FRONT. WINDS ARE FORECAST
TO DROP OFF LATER IN THE EVENING W/SOME FOG DEVELOPING,
ESPECIALLY IN AREAS THAT RECEIVED SOME RAINFALL.
HIGH PRES IS FORECAST TO MOVE IN QUICKLY ON TUESDAY W/SOME
SUNSHINE INITIALLY. CLOUDS WILL MOVE BACK IN QUICKLY BY THE
AFTERNOON AS THE HIGH MOVES OFF TO THE EAST. THE AIRMASS WILL
BECOME MORE TROPICAL BY THE LATE AFTERNOON. THE LEADING EDGE OF
THE RAIN FROM TC ISAIAS IS EXPECTED TO LIFTING INTO THE WRN AND
SWRN AREAS BY THE LATE AFTERNOON. FOR RAINFALL CHANCES, DECIDED
ON A BLEND OF THE GFS/NAM AND NBM W/THE HIGHEST PERCENTAGES
ACROSS THE WRN AND SWRN AREAS. MORE ON THIS IN THE SHORT TERM
SECTION BELOW.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
ISAIAS WILL BE THE MAIN SUBJECT IN THE SHORT TERM AS IT
ACCELERATES UP THE EAST COAST WITH HEAVY RAIN AND GUSTY WINDS.
ISAIAS IS FORECAST TO BE APPROACHING THE ME/NH BORDER TUESDAY
NIGHT INTO WEDNESDAY. ONGOING RAIN AHEAD OF THE SYSTEM WILL
CONTINUE TO SPREAD ACROSS THE CWA, WITH RAIN INTENSITY
INCREASING ACROSS THE NORTH WOODS AND CENTRAL HIGHLANDS. HEAVY
RAIN WILL BE LIKELY GIVEN ENVIRONMENTAL CONDITIONS W/ PWAT
VALUES SURGING WITH INTRODUCTION OF TROPICAL MOISTURE. THIS
INCLUDES PWATS CLOSING IN ON 2 INCHES AND MID/LOW LEVEL RH
VALUES AROUND 90%. CURRENT STORM TOTAL RAINFALL FORECASTS BRING
GREATEST TOTALS NORTH OF A LINE FROM BANGOR TO HOULTON WHERE 1
TO 2 INCHES WILL BE POSSIBLE. RAIN WITH THUNDERSTORMS WILL HAVE
THE POSSIBILITY TO DROP LOCALLY HIGHER AMTS, ESPECIALLY IF
TRAINING OCCURS. THIS RAISES CONCERN FOR FLASH FLOODING
POTENTIAL IN AREAS THAT SEE PERSISTENT ELEVATED RAINFALL RATES
DUE TO TERRAIN EFFECTS IN THE CENTRAL HIGHLANDS.
IT SHOULD BE NOTED THAT WHILE ISAIAS HAS BEEN FAIRLY IDLE
SLOWLY CHURNING OFF THE COAST OF FLORIDA, ITS FORWARD VELOCITY
WILL INCREASE INTO EARLY WEEK. THE HEAVY RAIN THREAT REMAINS DUE
TO PRECIP EFFICIENCY, BUT CLOUD LAYER MEAN WIND IS AROUND 60
KTS, A VERY RAPID PACE. THUS, FLASH FLOODING POTENTIAL WILL BE
CLOSELY MONITORED AHEAD OF THE EVENT AND AS IT UNFOLDS.
GUSTY WINDS WILL MAKE THEIR WAY INTO THE REGION TUESDAY NIGHT.
A POTENTIAL TRANSITION TOWARDS POST-TROPICAL CHARACTERISTICS
MAKES WIND FORECASTING TRICKY. WILL REPRESENT THE STRONGEST
WINDS ON EASTERN SIDE OF STORM CENTER; PENOBSCOT/FRENCHMAN BAY
TO BANGOR REGION TO CENTRAL HIGHLANDS TO SOUTHERN AROOSTOOK,
WITH SLACKENING GRADIENT TO THE WEST; THE NORTH WOODS. THESE
WINDS MAY STRETCH FURTHER OUT INTO THE GULF OF MAINE DESPITE
STORM CENTER FORECAST TRENDING INLAND. THIS APPEARS AS A POTENT
925 LLJ OF 40-55KTS VIA DETERMINISTIC GUIDANCE. SURFACE
INVERSION WILL OFFER SOME BUFFER FROM THESE WINDS REACHING THE
SURFACE, HOWEVER STRONGER SHOWERS OR THUNDERSTORMS MAY BRING
THESE WINDS DOWN ALONG THE COAST AND INTO THE LOWER PENOBSCOT
VALLEY EXTENDING THROUGH WED EARLY AFTERNOON.
RAIN WILL BEGIN TO TAPER TO SHOWERS WEDNESDAY AFTERNOON INTO THE
EVENING WITH MOSTLY DRY CONDITIONS EXPECTED OVERNIGHT INTO
THURSDAY.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
DRY PATTERN LOOKS LIKE IT WILL BE IN STORE RIGHT INTO THE
WEEKEND. HIGH PRES W/UPPER RIDGING IN CONTROL W/TEMPS REMAINING
WELL ABOVE AVERAGE. THERE IS AN UPPER TROF THAT IS FORECAST TO
SLIDE ACROSS THE REGION ON SATURDAY W/A SLIGHT COOLDOWN, BUT
REMAINING DRY. ANY RAINFALL ASSOCIATED W/THIS TROF IS FORECAST
TO BE S AND E OF THE CWA.
AVIATION /16Z MONDAY THROUGH FRIDAY/
NEAR TERM: GENERALLY MVFR TO LIFR CONDITIONS THIS MORNING WITH
LOW CLOUDS AND FOG, IMPROVING TO VFR THIS AFTERNOON. VARIABLE
CONDITIONS WITH ANY SHOWERS/THUNDERSTORMS THIS AFTERNOON.
TONIGHT: VFR W/BRIEF PERIODS OF MVFR FOR FOG. W WINDS BECOMING
LIGHT AND VARIABLE.
TUESDAY: VFR QUICKLY DROPPING TO MVFR BY LATE MORNING AND THEN TO
IFR. CHANCE OF RAIN LATE IN THE DAY. S WINDS INCREASING TO 10-15
MPH MPH LATER IN THE DAY.
SHORT TERM: FOR TUESDAY NIGHT INTO WEDNESDAY, MVFR GOING TO
IFR/LIFR W/POTENTIAL FOR HEAVY RAIN AND STRONG GUSTY WINDS.
IMPROVEMENT TO VFR LATER IN THE DAY ON WEDNESDAY.
WEDNESDAY NIGHT INTO THURSDAY...VFR FOR ALL TERMINALS WITH THE
POTENTIAL FOR SOME FOG LATER WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS COULD REDUCE CONDITIONS BRIEFLY TO MVFR/IFR. SW
WINDS 10 MPH BECOMING W.
THURSDAY NIGHT INTO FRIDAY...VFR. W WINDS 5 TO 10 MPH.
MARINE
NEAR TERM: WINDS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS
TODAY THROUGH TUESDAY. SEAS MAY REACH 5 FT OVER THE OFFSHORE
WATERS AT TIMES LATER TODAY INTO THIS EVENING. S WINDS WILL
SHIFT TO THE W TONIGHT AND DIMINISH TO LESS THAN 10 KT. SEAS
WILL BEGIN TO DIMINISH TONIGHT TO 3-4 FT BY TUESDAY MORNING.
LIGHT W WINDS SHIFTING TO THE S AND INCREASING TO AROUND 10 KT
BY LATE IN THE DAY.
SHORT TERM: TROPICAL STORM CONDITIONS WILL BE POSSIBLE AS ISAIAS
APPROACHES TUESDAY NIGHT INTO WEDNESDAY. SOUTHERLY WINDS
INCREASE WITH WAVE HEIGHTS INCREASING TOWARD 8 TO 10 FEET ON THE
COASTAL WATERS WEDNESDAY AFTERNOON. WINDS SHIFT SW, SLACKENING
BELOW SCA INTO THE EVENING AND OVERNIGHT. CONDITIONS LOOK TO
REMAIN BELOW SCA FOR REMAINDER OF PERIOD.
CAR WATCHES/WARNINGS/ADVISORIES
ME...TROPICAL STORM WATCH FOR MEZ001>006-010-011-015>017-029>032.
MARINE...TROPICAL STORM WATCH FOR ANZ050>052.
NEAR TERM...NORCROSS/HEWITT
SHORT TERM...CORNWELL
LONG TERM...CORNWELL
AVIATION...NORCROSS/HEWITT/CORNWELL
MARINE...NORCROSS/HEWITT/CORNWELL
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