568
FXUS61 KBOX 192008
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
308 PM EST TUE NOV 19 2024
SYNOPSIS
HIGH PRESSURE BUILDS IN FROM THE WEST AND BRINGS US ONE MORE
DRY/PLEASANT DAY ON WEDNESDAY. A SLOW-MOVING AND WELL-DEVELOPED
AREA OF LOW PRESSURE LOOKS TO SPREAD COOL OVERCAST CONDITIONS
ALONG WITH WELCOMED RAINS TO SOUTHERN NEW ENGLAND THURSDAY INTO
FRIDAY. RAIN COULD MIX WITH WET SNOW ABOVE 1500 FEET ELEVATION
BY FRIDAY. OUR WEATHER TURNS DRIER FOR THE WEEKEND INTO EARLY
NEXT WEEK, WITH A MIX OF CLOUDS AND SUN AND SEASONABLE
TEMPERATURES.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
310 PM UPDATE...
* DIMINISHING WIND TONIGHT WITH LOWS UPPER 20S & 30S
A WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST TONIGHT. THIS
WILL ALLOW WINDS TO BECOME CALM/LIGHT AND WITH MOSTLY CLEAR SKIES
SHOULD SEE A GOOD NIGHT OF RADIATIONAL COOLING. OVERNIGHT LOW TEMPS
ARE EXPECTED TO BOTTOM OUT IN THE UPPER 20S TO NEAR 30 IN THE
NORMALLY COLDEST LOW-LYING SPOTS WITH MAINLY 30S ACROSS THE URBAN
CENTERS.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
KEY POINTS...
* PLENTY OF SUNSHINE WED WITH HIGHS 55-60 & LIGHT WINDS
* INCREASING CLOUDS WED NIGHT WITH RAIN DEVELOPING 4-8 AM THU
DETAILS...
WEDNESDAY...
A MID LEVEL RIDGE AXIS WILL CROSS OUR REGION ON WED. THIS WILL
RESULT IN ANOTHER DAY OF PLENTY OF SUNSHINE...BUT MUCH LIGHTER WINDS
COMPARED TO THE LAST TWO DAYS. HIGH SHOULD TOP OFF MAINLY IN THE 55
TO 60 DEGREE RANGE.
WEDNESDAY NIGHT...
VIGOROUS NORTHERN STREAM ENERGY WILL BE DRIVING SOUTHEASTWARD ACROSS
THE GREAT LAKES WED NIGHT. AS THIS HAPPENS...SURFACE LOW PRESSURE
WILL INTENSIFY ACROSS THE GREAT LAKES AND ALSO LEAD TO SECONDARY
DEVELOPMENT SOUTH OF LONG ISLAND. THIS WILL INDUCE A MODEST ESE
LOW LEVEL JET AT 850 MB. WHILE WE EXPECT MUCH OF WED NIGHT TO
FEATURE DRY WEATHER...EXPECT CLOUDS TO BE ON THE INCREASE. A
SHIELD OF WIDESPREAD RAIN WILL THEN OVERSPREAD THE REGION FROM
SOUTHWEST TO NORTHEAST...ROUGHLY IN THE 4 TO 8 AM TIME FRAME.
OVERNIGHT LOW TEMPS SHOULD MAINLY BE IN THE UPPER 30S TO THE
LOWER 40S
LONG TERM /THURSDAY THROUGH TUESDAY/
HIGHLIGHTS:
* SLOW-MOVING FRONTAL SYSTEM BRINGS OVERCAST AND MUCH-WELCOMED RAINS
THURS INTO FRI, WHICH COULD MIX WITH WET SNOW AT LOCATIONS ABOVE
1500 FT ELEVATION THURS NIGHT AND FRI. TEMPS COOL TO SEASONABLE
LEVELS.
* TURNING DRIER THIS WEEKEND INTO EARLY NEXT WEEK, BUT STILL REMAINS
BLUSTERY AND SOMEWHAT UNSETTLED WITH SEASONABLE TEMPS.
* GRADUAL WARMING TREND EARLY NEXT WEEK.
DETAILS:
A SUBSTANTIAL PATTERN CHANGE TAKES PLACE IN THIS FORECAST PERIOD, AS
A DEEP AND SLOW-MOVING UPPER LEVEL LOW MOVING INTO THE NORTHEAST
BRINGS ABOUT A TREND TOWARD COOLER, CLOUDIER AND UNSETTLED WEATHER
AS WE MOVE INTO LATE THIS WEEK AND THE WEEKEND. HERALDING THAT
PATTERN CHANGE IS A FRONTAL SYSTEM MOVING IN LATE WED NIGHT INTO
FRI, IN WHICH THERE CONTINUES TO BE GROWING CONFIDENCE ON A
SIGNIFICANT RAIN EVENT WITH PERHAPS A LIGHT ACCUMULATION OF WET SNOW
IN THE HIGHEST OF ELEVATIONS INTO THURS NIGHT/FRI AS COLDER AIR
STARTS TO FILTER INTO THE REGION. WHILE SOME OF THE DETAILS ARE
STILL UNRESOLVED, IT IS A PATTERN THAT SHOULD BE MUCH WELCOMED WHEN
CONSIDERING THE PROTRACTED DRY WEATHER AND THE BRUSHFIRES HAVING
BROKEN OUT OVER THE PAST SEVERAL WEEKS IN SOUTHERN NEW ENGLAND.
WEDNESDAY NIGHT THROUGH FRIDAY:
INCREASING CLOUDS TOWARD OVERCAST IS EXPECTED WED NIGHT AS A
FRONTAL OCCLUSION MOVES INTO SOUTHERN NEW ENGLAND, WITH
POSSIBLE LOW PRESSURE DEVELOPMENT ALONG THE BOUNDARY OFFSHORE OF
LONG ISLAND AROUND LATE WED NIGHT/THURS. THIS FEATURE LOOKS TO
SPREAD WETTING RAINS TO SOUTHERN NEW ENGLAND BY THURS AM (POPS
INTO THE CATEGORICAL RANGE) WHICH THEN LIFTS GRADUALLY FROM
SOUTH TO NORTH. THIS FEATURE WILL BE WORKING WITH FAVORABLY
STRONG DYNAMICS FOR ASCENT, PRECIPITABLE WATER VALUES RISING TO
AROUND 0.7 TO 0.8 INCHES WITH AN UPSLOPE ENHANCEMENT GIVEN ESE
WINDS. BESIDES FOCUS ROUNDS OF STEADIER LIGHT TO MODERATE
INTENSITY STRATIFORM RAINS, WE COULD ALSO EASTERLY WINDS NEAR
THE SOUTH COASTAL WATERS REACH TO NEAR GALE FORCE FOR A TIME WED
NIGHT INTO EARLY ON THURS ESPECIALLY IF WE CAN GET A SECONDARY
AREA OF LOW PRESSURE TO DEVELOP ALONG THE OCCLUDED FRONTAL
BOUNDARY. THE LOCATION AND TRACK OF BOTH THE UPPER LEVEL LOW AND
SURFACE LOW PRESSURE ARE STILL A BIT UNCERTAIN, AS WELL AS THE
POTENTIAL FOR A DRIER PUNCH OF AIR ALOFT TO MOVE FROM SOUTH TO
NORTH LATER THURS NIGHT, WHICH COULD TRANSFORM INITIAL RAINS
THURS TO MORE OF AN INTERMITTENT/SHOWERY CHARACTER. BUT STILL,
ENSEMBLE QPF PROBS THROUGH THURS NIGHT SUPPORT HIGH (70-90%)
PROBS OF 24 HR RAINS OF AT LEAST A HALF INCH, WITH LOWER TO
MODERATE (15-60%, HIGHEST IN THE BERKSHIRES AND INTERIOR
SOUTHERN NEW ENGLAND) PROBS OF 24 HR RAINS OF AT LEAST AN INCH.
MOVING INTO THURS NIGHT AND FRI...COLDER AIR STARTS TO FILTER
IN ON WSW FLOW ALOFT. DYNAMIC COOLING ASSOCIATED WITH THE COLD
POCKET OF AIR ALOFT ALONG WITH CONTINUED QPF FALLING ACROSS
INTERIOR WESTERN NEW ENGLAND SHOULD FAVOR A GRADUAL TRANSITION
FROM RAIN OVER TO A MIX OF RAIN AND WET SNOW MIX AT ELEVATIONS
ABOVE ABOUT 1500 FT AGL. FOR THESE AREAS, IT IS A LITTLE EARLY
FOR ACCUMULATIONS AT THIS RANGE BUT ANY ACCUMULATION LIKELY
WOULD BE ON THE LIGHT SIDE WITH RAIN MIXING IN AT TIMES.
OTHERWISE, JUST LOOKING AT OVERCAST WITH MORE INTERMITTENT,
SHOWERY RAINS FOR THE VAST MAJORITY OF THE AREA FOR THURS NIGHT
AND FRI. A SECOND SPOKE OF ENERGY ROTATING AROUND THE BROAD
UPPER LOW LATE FRI INTO FRI NIGHT COULD BRING A PERIOD OF
STEADIER LIGHT RAINS TO EASTERN AND SOUTHEAST MA BUT ITS EXACT
PLACEMENT IS STILL UNCERTAIN.
TEMPERATURES...GRADUAL COLD ADVECTION TAKES PLACE IN THIS PERIOD,
TOWARD A SLOW COOLDOWN IN HIGH AND LOW TEMPS, ALTHOUGH PERSISTENT
OVERCAST ALSO FAVORS A NARROWER DIURNAL RANGE. SHOULD STILL SEE
HIGHS IN THE 40S/AROUND 50 IN THE INTERIOR AND LOWER 50S COASTAL
AREAS ON THURS, THEN COOLING OFF INTO THE 40S (UPPER 30S/LOW 40S
HIGHER TERRAIN) FRIDAY. LOWS IN THE MID 30S TO LOW 40S ON THURS
NIGHT, COOLING OFF INTO THE LOWER TO MIDDLE 30S FOR FRI NIGHT.
THE WEEKEND INTO EARLY NEXT WEEK:
STILL UNDER BROAD CYCLONIC FLOW ALOFT WITH A COOL POCKET OF AIR
WHICH COULD KEEP OUR WEATHER SOMEWHAT UNSETTLED, WITH AT LEAST
PARTLY TO MOSTLY CLOUDY WEATHER AROUND (MORE CLOUDS NORTH, LESS SO
SOUTH AND EAST). HOWEVER WE SHOULD START TO SEE A RETURN TO DRY
WEATHER BY THE WEEKEND. THOUGH IT MAY BE FAIRLY BLUSTERY IN THIS
PERIOD, TEMPS ALSO SLOWLY START TO MODERATE BACK INTO THE UPPER 40S
TO LOWER 50S, WHICH ARE CLOSE TO SEASONABLE.
AVIATION /20Z TUESDAY THROUGH SUNDAY/
FORECAST CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE...
THIS AFTERNOON AND TONIGHT...HIGH CONFIDENCE.
VFR. NW WIND GUSTS DIMINISH BY LATE AFTERNOON. WINDS THEN
GRADUALLY BECOME CALM/LIGHT NW TONIGHT.
WEDNESDAY...HIGH CONFIDENCE.
VFR. LIGHT N WINDS BECOMING NE.
WEDNESDAY NIGHT...MODERATE CONFIDENCE.
WE EXPECT CONDITIONS TO DETERIORATE TO MVFR-IFR LEVELS AS WED
NIGHT WEARS ALONG...BUT SPECIFIC TIMING OF THIS REMAINS
UNCERTAIN. WE ALSO EXPECT WIDESPREAD RAIN TO OVERSPREAD THE
INTERIOR TOWARD DAYBREAK AND BE ENTERING THE COASTAL PLAIN
SOMEWHERE IN THE VICINITY OF 12Z. NE WINDS 5-10 KNOTS BUT WE MAY
SEE SOME 20+ KNOT GUSTS DEVELOPING TOWARD DAYBREAK ALONG THE
COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. WINDY WITH
LOCAL GUSTS UP TO 30 KT. RA.
THURSDAY NIGHT: MAINLY MVFR, WITH AREAS IFR POSSIBLE. BREEZY.
RA.
FRIDAY: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. BREEZY. RA
LIKELY.
FRIDAY NIGHT: MAINLY MVFR, WITH LOCAL VFR POSSIBLE. RA LIKELY.
SATURDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. BREEZY. CHANCE
RA.
SATURDAY NIGHT: VFR. BREEZY. SLIGHT CHANCE RA.
SUNDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT AND WEDNESDAY...HIGH CONFIDENCE.
A RIDGE OF HIGH PRESSURE BUILDING IN FROM THE WEST WILL RESULT IN
CONDITIONS WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS TONIGHT AND
WED.
WEDNESDAY NIGHT...HIGH CONFIDENCE.
INTENSIFYING LOW PRESSURE OVER THE GREAT LAKES WILL ALLOW SECONDARY
DEVELOPMENT SOUTH OF LONG ISLAND. THIS WILL INDUCE AN EASTERLY LLJ
LATE WED NIGHT. WINDS/SEAS WILL BE BELOW SMALL CRAFT ADVISORY
THRESHOLDS FOR THE MAJORITY OF THE NIGHT. WIND GUSTS SHOULD PROBABLY
APPROACH SMALL CRAFT LEVELS TOWARD OR AROUND DAYBREAK THU. GIVEN IT
IS VERY LATE IN THE 3RD AND MAINLY 4TH PERIOD EVENT WILL LET THE
NEXT SHIFT HANDLE THE HEADLINES.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH
LOCAL GUSTS UP TO 30 KT. AREAS OF ROUGH SEAS. RAIN.
THURSDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS
WITH GUSTS UP TO 25 KT. ROUGH SEAS UP TO 11 FT. RAIN.
FRIDAY: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 10 FT. RAIN.
FRIDAY NIGHT: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS. RAIN.
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 25 KT. AREAS OF ROUGH SEAS. CHANCE OF RAIN.
SATURDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS
WITH GUSTS UP TO 25 KT. AREAS OF ROUGH SEAS. CHANCE OF RAIN.
SUNDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. AREAS OF ROUGH SEAS.
FIRE WEATHER
WEDNESDAY...
HIGH PRESSURE BUILDING IN FROM THE WEST WILL RESULT IN MUCH LIGHTER
WINDS WED COMPARED TO THE PRIOR TWO DAYS. MINIMUM AFTERNOON RELATIVE
HUMIDITY VALUES ARE EXPECTED TO BE BETWEEN 35 AND 50 PERCENT. AFTER
COLLABORATION WITH OUR AREA FIRE MANAGERS...WE WILL BE ISSUING A
SPECIAL WEATHER STATEMENT FOR WED FOR THE ENTIRE REGION ONCE THE
CURRENT RFW EXPIRES AT 6 PM.
THURSDAY INTO FRIDAY...
A MUCH NEEDED WIDESPREAD 1" TO 1.50" OF RAIN IS ON TAP FOR THU INTO
FRI WITH EVEN LOCALIZED 2"+ AMOUNTS POSSIBLE ACROSS THE INTERIOR.
THIS SHOULD RESULT IN SIGNIFICANT EASING OF THE CURRENT FIRE WEATHER
CONCERNS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...RED FLAG WARNING UNTIL 6 PM EST THIS EVENING FOR MAZ002>024-
026.
RI...NONE.
MARINE...NONE.
SYNOPSIS...FRANK/HRENCECIN
NEAR TERM...FRANK
SHORT TERM...FRANK
LONG TERM...HRENCECIN
AVIATION...FRANK/HRENCECIN
MARINE...FRANK/HRENCECIN
FIRE WEATHER...FRANK
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