611
FXUS61 KBOX 041954
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
254 PM EST SUN DEC 4 2022
SYNOPSIS
DRY AND CHILLY WEATHER TONIGHT, WITH A WARMING TREND MONDAY THROUGH
MID WEEK. BREEZY WITH RAIN TUESDAY THROUGH LATE WEDNESDAY. DRIER
ON THURSDAY. TEMPERATURES TRENDING MORE SEASONABLE LATE THIS
WEEK THROUGH THE WEEKEND.
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
HIGH PRESSURE WILL PASS BY SOUTHERN NEW ENGLAND TONIGHT. THIS
WILL RESULT IN WINDS BECOMING LIGHT AND VARIABLE. ALREADY SEEING
SOME HIGH LEVEL CLOUDS OVERSPREADING OUR REGION, SO NOT
EXPECTING IDEAL RADIATIONAL COOLING CONDITIONS. THAT SAID, DID
FAVOR THE LOWER END OF THE TEMPERATURE GUIDANCE, WITH LOW
TEMPERATURES ABOUT 10-15 DEGREES LOWER THAN THIS MORNING. THE
MORE URBANIZED AREAS WILL NOT COOL OFF QUITE AS MUCH, BUT SHOULD
STILL BE COLDER THAN THIS MORNING.
SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/
HIGH PRESSURE TO OUR EAST CONTINUES TO MOVE OFFSHORE DURING THE
DAY. EXPECTING A LIGHT SOUTH TO SOUTHWEST WIND TO DEVELOP DURING
THE DAY, WHICH THEN SHOULD BECOME SOUTH TO SOUTHEAST MONDAY
NIGHT. THE COLD START, COUPLED WITH THE LOW DECEMBER SUN ANGLE,
WILL LIMIT THE WARMING AT THE SURFACE. NONETHELESS, STILL
EXPECTING HIGH TEMPERATURES TO BE SLIGHTLY ABOVE NORMAL.
INCREASING CLOUDINESS MONDAY NIGHT AHEAD OF A COLD FRONT, WITH A
SERIES OF WEAK SHORTWAVES. STILL ANTICIPATING DRY CONDITIONS FOR
JUST ABOUT ALL OF OUR REGION. THE LOWER LEVELS SHOULD BE QUITE
DRY, AND IT WILL TAKE SOME TIME TO INCREASE HUMIDITY TO THE
POINT WHERE PRECIPITATION WILL REACH THE GROUND. CONFINED
RAINFALL CHANCES MAINLY WEST OF THE CT RIVER VALLEY LATE MONDAY
NIGHT.
LONG TERM /TUESDAY THROUGH SATURDAY/
HIGHLIGHTS
* UNSETTLED TUESDAY THROUGH LATE WEDNESDAY WITH RAIN. MAY BE A BIT
BREEZY AT TIMES WITH WARMER THAN NORMAL TEMPS.
* DRIER ON THURSDAY AND A BIT COOLER, BUT TEMPS STILL ROUGHLY 5
DEGREES WARMER THAN NORMAL.
* CONFIDENCE LOWERS SIGNIFICANTLY LATE IN THE WEEK THROUGH THE
WEEKEND. HIGHER CONFIDENCE IN TEMPERATURES TRENDING NEAR TO COOLER
THAN NORMAL.
TUESDAY THROUGH WEDNESDAY...
CYCLONIC FLOW IN PLACE THROUGH THIS PERIOD. WILL HAVE TWO SHORTWAVES
LIFT THROUGH WELL TO THE NORTHWEST OF OUR REGION. THE FIRST MOVES
FROM THE CENTRAL GREAT LAKES EARLY ON TUESDAY INTO CENTRAL QUEBEC BY
LATE TUESDAY. THE NEXT SHORTWAVE LIFTS FROM THE MID/UPPER
MISSISSIPPI RIVER VALLEY LATE ON TUESDAY INTO SOUTHERN/EASTERN
QUEBEC BY LATE WEDNESDAY. LOW PRESSURE WILL LIFT ACROSS CENTRAL AND
NORTHERN QUEBEC ON TUESDAY, WHICH WILL LIFTS A PSEUDO WARM FRONT
INTO OUR REGION WHILE THE COLD FRONT SLIDES INTO THE EASTERN GREAT
LAKES. A BROAD LOW DEVELOPS OVER THE MID ATLANTIC ON WEDNESDAY AND
LIFTS NORTHEASTWARD, WHICH WILL PUSH THE COLD FRONT THROUGH LATER ON
WEDNESDAY.
MAIN CONCERN DURING THIS PERIOD IS THE POTENTIAL FOR STRONG WIND
GUSTS LATE ON TUESDAY THROUGH WEDNESDAY AS A S/SSW 30-40 KT LOW
LEVEL JET SLIDES THROUGH AT 925 HPA. STILL APPEARS THAT WE HAVE
ROUGHLY A 1-2 STD ABOVE MODEL CLIMATOLOGY WITH THE NAEFS FOR WIND
SPEED DURING THIS PERIOD. THINK THAT THE RISK FOR THE STRONGEST WIND
GUSTS WILL BE ON WEDNESDAY AS JET IS SLIDING ACROSS THE REGION AND
AS THE COLD FRONT IS SLIDING THROUGH. SINCE YESTERDAY CONFIDENCE IS
LOWERING ON THE RISK OF STRONG WINDS THROUGH THIS PERIOD AS BUFKIT
SOUNDINGS CONTINUE TO SHOW AN INVERSION IN PLACE PER THE GFS/NAM
GUIDANCE. STILL MAY BE A BIT BREEZY AT TIMES GIVEN THE TIGHTENED
PRESSURE GRADIENT, BUT APPEARING THAT IT WILL BE DIFFICULT TO TAP
INTO THE STRONGER WINDS ALOFT.
SHOULD SEE ANYWHERE FROM 0.5 TO 1.5 INCHES OF RAINFALL THROUGH THIS
PERIOD. AT THIS POINT AM THINKING THAT THE HEAVIEST RAINS WILL BE
LATE ON TUESDAY UNTIL ROUGHLY WEDNESDAY AFTERNOON FROM WEST TO EAST.
THIS COINCIDES WITH THE UPTICK IN THE S/SSW LOW LEVEL JET SLIDING
THROUGH AND PWATS INCREASING TO ROUGHLY 1-1.25 INCHES. THIS IS
ROUGHLY BETWEEN THE 90TH AND MAX PER SPC SOUNDING CLIMATOLOGY FOR
CHH.
TEMPERATURES WILL CLIMB ABOVE NORMAL DUE TO SOUTHERLY WARM AIR
ADVECTION. EXPECT TEMPERATURES TO CLIMB TO ROUGHLY 5-8 DEGREES
CELSIUS ON TUESDAY AND 7-11 DEGREES ON WEDNESDAY. SHOULD SEE FAIRLY
WIDESPREAD 50S ON BOTH DAYS WITH WEDNESDAY BEING THE WARMER OF THE
TWO DAYS. NOT COMPLETELY OUT OF THE QUESTION A FEW SPOTS IN THE
MERRIMACK AND CT RIVER VALLEY APPROACH 60 DEGREES ON WEDNESDAY.
THURSDAY...
CYCLONIC FLOW BEGINNING TO BREAK DOWN AS WE START TO SEE A PATTERN
CHANGE. THIS IS A RESULT OF THE TROUGH LIFTING OUT OF THE
SOUTHWESTERN US INTO THE CENTRAL US/MID MISSISSIPPI RIVER VALLEY.
AHEAD OF THIS FEATURE WE WILL HAVE A RIDGE BUILD FROM THE MID
MISSISSIPPI RIVER VALLEY INTO THE EASTERN GREAT LAKES. HIGH PRESSURE
WILL NUDGE INTO THE REGION FROM ONTARIO/QUEBEC.
STILL COULD SEE A FEW LINGERING SHOWERS ACROSS EASTERN PORTIONS OF
SOUTHERN NEW ENGLAND EARLY ON THURSDAY AS THE COLD FRONT MAY STILL
BE EXITING. WILL BE A DRIER AND COOLER AS FLOW SHIFTS TO THE NW/N.
SOME UNCERTAINTY ON THE EXACT TEMP READINGS GIVEN MODELS ARE SPREAD
IN THE AIRMASS IN PLACE ALOFT. GIVEN THE UNCERTAINTY HAVE STUCK WITH
THE NBM. THIS KEEPS TEMPS RANGING FROM THE MID 40S TO THE MID 50S.
FRIDAY THROUGH THE WEEKEND...
CONFIDENCE LOWERS SIGNIFICANTLY DURING THIS PERIOD DUE TO THE TROUGH
LIFTING IN FROM THE CENTRAL US/MID MISSISSIPPI RIVER VALLEY. QUITE A
BIT OF SPREAD AMONGST DETERMINISTIC GUIDANCE WITH THE INTENSITY AND
PROGRESSION OF THIS FEATURE AS IT SLIDES IN.
AT THIS POINT APPEARS THAT THERE WILL BE A LEAST SOME PRECIPITATION
PER CLUSTER ANALYSIS OF ENSEMBLE GUIDANCE. THE MAIN SOURCE OF
VARIANCE IS HOW DEAMPLIFIED/AMPLIFIED THE RIDGE IS OVER NOVA SCOTIA
AND THE SECONDARY IS THE EXACT POSITION OF THE RIDGE. DOES APPEAR
THAT THERE WILL BE AT LEAST SLIGHT CHANCES TO CHANCES OF
PRECIPITATION THROUGH THIS TIMEFRAME AS THE MAJORITY OF ENSEMBLE
MEMBERS FEATURE THIS. WILL NOTE THAT THERE ARE A HANDFUL OF MEMBERS
IN THE EPS/GEFS AND GEPS GUIDANCE THAT HAVE A SIMILAR FEEL OF THE
LATEST OPERATIONAL GFS, BUT IT IS STILL MUCH TOO EARLY TO LATCH ONTO
THIS GIVEN THE SPREAD AMONGST GUIDANCE. DUE TO THIS HAVE JUST STUCK
WITH THE NBM. THIS KEEPS TEMPS NEAR TO SLIGHTLY COOLER THAN
SEASONABLE.
AVIATION /20Z SUNDAY THROUGH FRIDAY/
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT AND MONDAY...HIGH CONFIDENCE.
VFR THROUGH MONDAY. W TO NW WINDS BECOMING LIGHT AND VARIABLE
TONIGHT. S TO SW WINDS DEVELOPING MONDAY.
MONDAY NIGHT...MODERATE CONFIDENCE.
MAINLY VFR, WITH AREAS OF MVFR OR LOCAL IFR POSSIBLE ACROSS THE
HIGHER TERRAIN. WINDS BECOMING S TO SE.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /TUESDAY THROUGH THURSDAY/...
MONDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY.
SLIGHT CHANCE FZRA.
TUESDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY. CHANCE
RA.
TUESDAY NIGHT: MAINLY VFR, WITH AREAS IFR POSSIBLE. BREEZY. RA.
WEDNESDAY: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. RA.
WEDNESDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY.
CHANCE RA.
THURSDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
HIGH CONFIDENCE. RELATIVELY LIGHT WINDS AND SEAS FOR EARLY
DECEMBER AS A HIGH PRESSURE MOVES OVER THE WATERS TONIGHT, THEN
FARTHER OFFSHORE MONDAY. A FEW WIND GUSTS COULD APPROACH 25 KT
ACROSS THE EASTERN COASTAL WATERS MONDAY AFTERNOON. SEAS
CONTINUE TO SUBSIDE, SO ANTICIPATING BEING ABLE TO LOWER SMALL
CRAFT ADVISORIES LATER TODAY.
OUTLOOK /TUESDAY THROUGH THURSDAY/...
MONDAY NIGHT: WINDS LESS THAN 25 KT.
TUESDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.
CHANCE OF RAIN.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. RAIN
LIKELY.
WEDNESDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS
UP TO 25 KT. SEAS UP TO 5 FT. RAIN.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. CHANCE
OF RAIN.
THURSDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ250-
254>256.
SYNOPSIS...BELK/BL
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...BL
AVIATION...BELK/BL
MARINE...BELK/BL
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