571
FXUS61 KBOX 202024
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
324 PM EST MON JAN 20 2025
SYNOPSIS
AN ARCTIC AIRMASS WILL BRING FRIGID CONDITIONS WITH MINIMUM
WIND CHILLS ON THE ORDER OF 0 TO 15 BELOW ZERO AT TIMES THROUGH
WEDNESDAY MORNING. TEMPERATURES MODERATE A BIT THURSDAY AND
FRIDAY, BUT THEY WILL REMAIN BELOW NORMAL. DRY WEATHER WILL
GENERALLY PREVAIL THE REST OF THIS WEEK...BUT WILL NEED TO WATCH
A COUPLE DISTANT WAVES OF LOW PRESSURE IN CASE THEY TREND
FURTHER NORTHWEST.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
KEY MESSAGE
* BITTER COLD TEMPERATURES ACROSS SOUTHERN NEW ENGLAND TONIGHT WITH
SINGLE DIGIT LOW TEMPERATURES FORECAST ACROSS THE REGION
* COLD WEATHER ADVISORY IN EFFECT FOR THE NORTH EAST SLOPES OF
THE BERKSHIRES AND NORTHERN WORCESTER COUNTY
TONIGHT
GUSTY NORTHWEST WINDS THIS AFTERNOON GRADUALLY DIMINISH/DECOUPLE
AFTER SUNSET. CLEAR SKIES, A FRESH SNOW PACK, AND LIGHT WINDS SHOULD
SUPPORT VERY EFFICIENT RADIAIONAL COOLING THAT WILL ALLOW
TEMPERATURES TO DIP INTO THE SINGLE DIGITS FOR MOST OF INTERIOR
SOUTHERN NEW ENGLAND. SOME LOCATIONS ACROSS INTERIOR MA AT THE
HIGHER ELEVATIONS MAY EVEN APPROACH 0. WHILE WINDS WILL BE ON THE
LIGHER SIDE, THERE WILL BE AT LEAST SOME MECHANICAL MIXING THAT WILL
LIMIT A MAXIMUM RADIATIONAL COOLING EFFECT, BUT NONETHELESS WIND
CHILL TEMPERATURES WILL BE WELL BELOW 0 ACROSS THE INTERIOR
OVERNIGHT AND INTO TOMORROW MORNING. THE COASTAL LOCATIONS WILL GET
SOME MILD RELIEF FROM THE PROXMITIY TO THE REALTIVELY WARMER OCEAN,
BUT WILL STILL EXPERIENCE SINGLE DIGIT WIND CHILL VALUES OR
LOWER.
SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/
KEY MESSAGES
* BITTER COLD TEMPERATURES CONTINUE TOMORROW AND PEAK TOMORROW NIGHT
* COLD WEATHER HEADLINES LIKELY AGAIN TOMORROW NIGHT
TOMORROW AND TOMORROW NIGHT
THE ARCTIC OUTBREAK PEAKS TOMORROW AND TOMORROW NIGHT AS 925 HPA
TEMPS CONTINUE TO OVER AT -15C OR LOWER. EXPECT SUNNY SKIES ACROSS
THE INTERIOR NORTH OF I-90 TOMORROW, BUT ACROSS CT, RI, AND
SOUTHEASTERN MA THERE WILL BE INCREASING CLOUDINESS AS A PLUME OF
MOISTURE AT 850 HPA EDGES OVER THE REGION. HIGH TEMPERATURES WILL
STRUGGLE TO BREAK OUT OF THE TEENS ACROSS THE INTERIOR TOMORROW, BUT
THE COASTAL LOCATIONS WILL BE A BIT MORE MILD IN THE LOW TO MID 20S.
STEADY WEST/NORTHWEST WINDS FROM 10-15 MPH WILL ADD A WIND CHILL
FACTOR THAT WILL HAVE THE DAY TIME TEMPERATURES FEELING CLOSER TO
THE SINGLE DIGITS/LOW TEENS THAN THE TEENS AND LOW 20S.
AFTER SUNSET, THE ATOMSPHERE DECOUPLES ALLOWING TEMPERAUTRES TO DIP
ONCE AGAIN. CLOUDS OVER THE SOUTHERN HALF OF THE FORECAST AREA
RETREAT SOUTH AND EAST AND ALSO MAY PRODUCE SOME LIGHT SNOW OVER
NANTUCKET/MARTHAT'S VINEYARD, BUT NO SUBSTANTIAL ACCUMULATIONS WOULD
BE EXPECTED. AREAS WITH CLOUD COVER TO BEGIN WITH MAY NOT RADIATE AS
EFFICIENTLY AS THEY WOULD OTHERWISE ON A CLEAR NIGHT, BUT CLEARER
SKIES ACROSS THE INTERIOR WILL SUPPORT THE COLDEST TEMPERATURES
DURING THIS STRETCH. MANY LOCATIONS WILL HAVE SINGLE DIGIT OR
NEGATIVE SINGLE DIGIT TEMPERATURES BY WEDNESDAY MORNING. WITH WIND
CHILL TEMPERATURES WELL BELOW -15F, FOR SEVERAL LOCATIONS WEST OF I-
95, COLD WEATHER HEADLINES WILL LIKELY BE NEEDED FOR A SECOND NIGHT.
LONG TERM /WEDNESDAY THROUGH MONDAY/
KEY MESSAGES:
* BITTERLY COLD WEDNESDAY MORNING FOLLOWED BY HIGHS THAT ONLY REACH
THE LOWER 20S
* SINGLE DIGIT LOWS WEDNESDAY NIGHT BEFORE TEMPERATURES BEGIN TO
MODERATE THURSDAY, ALTHOUGH STILL EXPECTED TO BE BELOW NORMAL
* DRY THROUGHOUT ASIDE FROM SOME STRAY SNOW SHOWER CHANCES TOWARDS
THE CAPE FRIDAY AM
WEDNESDAY
AN ARCTIC AIRMASS REMAINS SETTLED OVER THE REGION BEFORE IT BEGINS
TO MAKE ITS EXIT THURSDAY. TEMPERATURES AT 850 MB WEDNESDAY CONTINUE
TO SIT IN THE -25C TO -20C RANGE AND FORECAST SOUNDINGS INDICATE DRY
CONDITIONS WITH GOOD MIXING, CONTINUING THIS COLD TREND. ENSEMBLES
SHOW GOOD PROBS FOR TEMPERATURES BELOW 5F FOR WEDNESDAY NIGHT
PARTICULARLY ACROSS THE INTERIOR AND TOWARDS THE MERRIMACK VALLEY.
WIND CHILL VALUES WED PM COULD ONCE AGAIN REACH THE NEGATIVES IN
SOME SPOTS. SOME MID TO HIGH LEVEL CLOUDS COULD HELP KEEP
TEMPERATURES FROM SINKING AS LOW AS THEY ARE EXPECTED TO FOR TUESDAY
NIGHT, BUT THEY CONTINUE TO RANGE FROM CLOSE TO 0F TO THE LOW TEENS
AS YOU MOVE FROM THE INTERIOR TO THE COAST.
THURSDAY AND FRIDAY
A RIDGE OF HIGH PRESSURE PROGRESSES EAST OF THE REGION BY THURSDAY,
AND MILDER AIR MAKES ITS WAY ACROSS SOUTHERN NEW ENGLAND.
TEMPERATURES ALOFT ARE STILL LOW, BUT THEY IMPROVE TO THE -15C TO -
10C RANGE AT 850 MB BY THE DAYTIME HOURS. HIGHS ARE STILL EXPECTED
TO BE IN THE 20S AND 30S FOR BOTH THURS AND FRI, BUT IT'S AN
IMPROVEMENT NONETHELESS. WITH THE SNOWPACK ACROSS MUCH OF THE REGION
AND CLEARER SKIES THURSDAY NIGHT, LOWS ARE STILL LIKELY TO TANK INTO
THE SINGLE DIGITS AND LOW TEENS OUTSIDE OF THE CAPE AND ISLANDS, AS
THEY DON'T HAVE AS SIGNIFICANT OF A SNOWPACK AND MAY SEE MORE CLOUD
COVER LINGERING DURING THE OVERNIGHT HOURS. WINDS ARE EXPECTED TO
REMAIN LIGHT AND MOSTLY FROM THE W TO NW THROUGH BOTH DAYS.
THE SHORTWAVE ASSOCIATED WITH THE WINTER WEATHER IN THE SOUTHERN US
MOVES EASTWARD THURSDAY NIGHT INTO FRIDAY MORNING, HOWEVER WE'RE NOT
EXPECTING ANY SIGNIFICANT IMPACTS AT THIS TIME. AT MOST, SOME STRAY
SNOW SHOWERS OVER THE CAPE COULD DEVELOP, BUT THE SIGNAL IN THE
ENSEMBLE GUIDANCE STILL VARIES A BIT AT THIS POINT. THE ECMWF
ENSEMBLE FAVORS A DRIER SOLUTION WHILE THE CANADIAN IS MORE
AGGRESSIVE ON THE CHANCE FOR SOME PRECIPITATION.
SATURDAY THROUGH MONDAY
TEMPERATURES CONTINUE TO MODERATE AND DRY CONDITIONS CONTINUE
THROUGH THE WEEKEND. DEEP TROUGHING OVER THE SW US WILL ENCOURAGE
GEOPOTENTIAL HEIGHTS TO RISE OVER THE SE US. ENSEMBLE HEIGHT
ANOMALIES ALSO INDICATE HEIGHT FALLS TO OUR NORTH AND WEST, AND AN
AREA OF LOW PRESSURE TO THE N AND NE WITH HIGH PRESSURE TO THE SW AT
THE SURFACE IS A FAVORED OUTCOME. SO THE DIFFERENCE BETWEEN THE
BUILDING HEIGHTS IN THE SOUTH AND THE FALLING HEIGHTS IN THE NORTH
LEADING TO THIS BUILDING PRESSURE GRADIENT AT THE SURFACE WILL
ENCOURAGE THE DEVELOPMENT OF SLIGHTLY STRONGER W TO SW WINDS OVER
THE WEEKEND WITH GUSTS UP TO 25 OR 30 MPH POSSIBLE.
WITH THE CONTINUED MODERATION OF TEMPERATURES DUE TO THIS SW FLOW,
HIGHS SUNDAY ARE EXPECTED TO BE ABOVE FREEZING FOR MUCH OF THE
REGION. SOME SPOTS COULD REACH OVER 40F. BEYOND THIS PERIOD, SOME
LOW PRECIPITATION CHANCES SHOW UP FOR LATER MONDAY, BUT NOTHING
SIGNIFICANT AT THIS TIME.
AVIATION /21Z MONDAY THROUGH SATURDAY/
FORECAST CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z UPDATE:
TODAY...HIGH CONFIDENCE.
THROUGH 00Z...HIGH CONFIDENCE.
VFR. NORTHWEST WINDS AROUND 10 KNOTS. 20+ KNOT GUSTS BEGIN TO
DIMINISH AFTER 21-22Z.
TONIGHT...HIGH CONFIDENCE
VFR. WINDS BECOMING WSW AROUND 5 KNOTS OR LESS.
TOMORROW...HIGH CONFIDENCE
VFR. WSW WINDS AROUND 10 KNOTS. INCREASING MID-LEVEL CLOUDINESS
DURING THE AFTERNOON.
TOMORROW NIGHT...HIGH CONFIDENCE
VFR. WINDS SHIFT BACK TO THE NORTHWEST WITH SPEEDS AROUND 5
KNOTS.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: VFR. BREEZY.
WEDNESDAY NIGHT THROUGH FRIDAY NIGHT: VFR.
SATURDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH- GREATER THAN 60 PERCENT.
TONIGHT THROUGH TOMORROW NIGHT
HIGH CONFIDENCE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH TONIGHT AND
TOMORROW FOR THE OUTER MARINE ZONES. ARCTIVE AIR MASS SETTLES IN
TONIGHT AND PERSISTS THROUGH WEDNESDAY SUPPORTING PERIODS OF
SPREEZING SPRAY. WINDS WILL BE REALTIVELY MODEST IN THE 10 TO 20
KNOT RANGE OUT OF THE WEST/NORTHWEST WITH SOME GUSTS UP TO 25
KNOTS. SEAS GENERALLY RANGING FROM 2 TO 4 FEET.
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT.
THURSDAY THROUGH THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS
LOCALLY APPROACHING 5 FT. SLIGHT CHANCE OF SNOW.
FRIDAY THROUGH FRIDAY NIGHT: WINDS LESS THAN 25 KT.
SATURDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
TUESDAY FOR MAZ002-004-008.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
ANZ230>234-236.
SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR ANZ250-254>256.
SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ251.
SYNOPSIS...FRANK/MENSCH
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...HRENCECIN
AVIATION...HRENCECIN/RM
MARINE...HRENCECIN/RM
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