363  
FXUS61 KBOX 222246  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
546 PM EST FRI FEB 22 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER THE GREAT LAKES BUILDS INTO NEW ENGLAND  
TONIGHT AND SATURDAY, THEN MOVES OFFSHORE SATURDAY EVENING.  
THIS WILL BRING A PERIOD OF DRY AND SEASONABLY COOL WEATHER TO  
THE REGION. LOW PRESSURE THEN TRACKS ALONG THE COAST SUNDAY WITH  
A WIND SWEPT RAIN, EXCEPT FREEZING RAIN/ICE FOR THE INTERIOR  
SUNDAY MORNING. STRONG TO DAMAGING WINDS DEVELOP SUNDAY NIGHT,  
PEAKING AROUND MONDAY THEN GRADUALLY DIMINISHING INTO TUESDAY. A  
MOSTLY QUIET WEEK THEREAFTER, WATCHING A POTENTIAL FOLLOWING  
WEEKEND STORM.  
 

 
   
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
 
 
330 PM UPDATE...  
 
1033 MB HIGH PRESSURE OVER THE GREAT LAKES ADVECTS INTO NEW  
ENGLAND TONIGHT RESULTING IN WINDS DIMINISHING WITH SUNSET.  
FAIRLY DRY ATMOSPHERE WITH DEW PTS IN THE UPPER TEENS AND 20S  
COMBINED WITH JUST SOME THIN CIRRUS CLOUDS SPILLING OVER THE  
RIDGE TO OUR WEST, WILL PROMOTE RADIATIONAL COOLING TONIGHT.  
THUS TEMPS WILL FALL FAIRLY QUICKLY AFTER SUNSET. THEREFORE HAVE  
BASED MINS TONIGHT ON THE COLDER MOS GUIDANCE. LOWS WILL RANGE  
FROM THE UPPER TEENS TO LOWER 20S, MID 20S IN THE URBAN AREAS OF  
BOSTON, PROVIDENCE AND HARTFORD.  
 

 
   
SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/
 
 
330 PM UPDATE...  
 
SATURDAY...  
 
VERY NICE DAY BY LATE FEB STANDARDS WITH PLENTY OF SUNSHINE AS DEEP  
LAYER RIDGE AXIS REMAINS JUST WEST OF NEW ENGLAND SUPPORTING ANTI-  
CYCLONIC FLOW AND ASSOCIATED SUBSIDENCE INTO MA/RI/CT. PERHAPS SOME  
MID/HIGH CLOUDS DIMMING THE SUN LATE IN THE DAY BUT OTHERWISE  
ABUNDANT SUNSHINE.  
 
1032 MB HIGH PRES OVER THE REGION TOMORROW WILL PROMOTE LIGHT WINDS.  
THUS THIS COMBINED WITH FULL SUNSHINE AND HIGHS CLIMBING INTO THE  
LOWER 40S WILL MAKE FOR VERY PLEASANT LATE WINTER CONDITIONS. LITTLE  
COOLER ALONG THE COAST AS LIGHT ONSHORE WINDS DEVELOP IN THE AFTERNOON.  
 
SATURDAY NIGHT ...  
 
WINTRY MESS MOVING IN CLOSER TO MIDNIGHT. COLD AIR WEDGED IN THAT'LL  
PERSIST WITH WET-BULBING / EVOLVING N-DRAINAGE FLOW. SUB-FREEZING  
AIR GRADUALLY SCOURING OUT THROUGH A NOCTURNAL EVENT. EVALUATING  
MAX WET-BULB WITHIN H925-7 LAYER, NON-GFS PREFERENCE, BRIEF ONSET  
SNOW / SLEET TRANSITIONING SW TO NE QUICKLY TO INTERIOR FREEZING  
RAIN, COASTAL RAIN, AS LATEST SUITE OF FORECAST GUIDANCE HAS COME  
IN WARMER. FREEZING RAIN LIKELY TO HOLD OUT RIGHT THROUGH SUNDAY  
MORNING FOR INTERIOR VALLEYS, ESPECIALLY PIONEER AND MERRIMACK,  
ESPECIALLY AS A SECONDARY SURFACE LOW DEVELOPS. TRACE SNOW / SLEET,  
MAINLY A FREEZING RAIN EVENT OF A COATING TO AROUND 0.2.  
 

 
   
LONG TERM /SUNDAY THROUGH FRIDAY/
 
 
*/ HIGHLIGHTS ...  
 
- LINGERING INTERIOR FREEZING RAIN EARLY SUNDAY, OTHERWISE RAIN  
- DRYING OUT LATE SUNDAY  
- STRONG, DAMAGING WINDS AROUND MONDAY, WIND HEADLINES LIKELY  
- COULD BE QUIET AND DRY THROUGH THE WEEK, WEEKEND STORM POSSIBLE  
 
*/ OVERVIEW ...  
 
POLEWARD LATENT HEAT RELEASE TRANSFERS ACROSS BOTH THE N ATLANTIC  
AND N PACIFIC CONTRIBUTING TO STOUT RIDGING OVER W EUROPE AND AK,  
RESPECTIVELY. ARCTIC SQUEEZE-PLAY, N-STREAM ENERGY BOWLED S OVER N  
AMERICA, CROSS-POLAR FLOW INTO THE CONUS COURTESY AK RIDGING AS THE  
NW ATLANTIC REMAINS WIDE OPEN. WITH A MILD PACIFIC STREAM PERSISTING  
FROM FAVORABLE HAWAIIAN TROUGHING INTO THE W CONUS IT REMAINS TO BE  
SEEN AS TO WHETHER S-STREAM ENERGY WILL BUCKLE OR RATHER PHASE WITH  
DIVING N-STREAM, WHETHER A FLAT TROF-BASE FLOW WITH PARENT THERMAL  
GRADIENT OR RATHER MORE PRONOUNCED TROUGHING EMERGES WITH CONVEYOR  
BELT MOTIONS, RESPECTIVELY. WILDCARDS WITH TYPHOON WUTIP, AS WELL AS  
TRANSITIONING ENHANCED TROPICAL CONVECTION ACROSS THE ATLANTIC INTO  
THE INDIAN OCEAN SIGNALED VIA THE PHASE 8 TO PHASE 3 FORECAST MJO  
VIA EC, ANOMALOUS MILD WESTERLIES SHIFTING DOWNSTREAM ACCORDINGLY.  
 
A LOT PLAYING OUT INTO THE END OF FEBRUARY, ACCOMPANYING NUISANCES.  
AFTER THE WEEKEND / EARLY WEEK WINTRY MESS FOLLOWED BY STRONG TO  
DAMAGING WINDS THERE'S NOT A LOT OF FORECAST CONFIDENCE. CERTAIN  
THAT ARCTIC AIR WILL MAKE ITS PRESENCE WELL-KNOWN, BUT UNCERTAINTY  
CONCERNING ANY STORM MORPHOLOGY AND ACCOMPANYING AIRMASS. IF THE  
FORECAST EPO REMAINS LARGELY NEGATIVE AS THE EC SUGGESTS, PREFER TO  
LEAN COLDER BENEATH A CONTINENTAL-POLAR AIRMASS, THE MORE FAVORABLE  
BAROCLINIC ZONE SHUNTED WELL S OF OUR REGION. LIGHTER YET WINTRY  
OUTCOMES WITH THE BETTER STORM-TRACK WELL OUTSIDE OUR AREA, OUT TO  
SEA. PREFERENCE TO THE EC / ECENS GUIDANCE. BREAK DOWN THE DETAILS  
BELOW.  
 
*/ DISCUSSION ...  
 
SUNDAY ...  
 
CONTINUING INTERIOR FREEZING RAIN. PREFER MAINTAINING A SHALLOW COLD  
AIRMASS GIVEN SECONDARY COASTAL LOW FORECAST. N-WEDGE DRAINAGE FLOW  
WITH AGEOSTROPHIC / ISALLOBARIC WINDS, SLOWLY SCOURING OUT WITH RAIN  
RELEASING LATENT HEAT AT THE SURFACE AS OVER TIME IT FALLS THROUGH A  
DEEPER H9-7 WARM LAYER. MAINTAIN FREEZING RAIN AS LATE AS MIDDAY BY  
WHICH POINT THE ATTENDANT STORM SYSTEM / FRONTAL BOUNDARIES SHOULD  
BE LIFTING N RESULTING IN ANY N WINDS TO SHIFT W/SW. ADDITIONAL ICE  
ACCRETION OF A COATING UP TO 0.1 INCHES MAINLY FOCUSED OVER N/W MA.  
ICING ON UNTREATED SURFACES, SLICK AND HAZARDOUS.  
 
SUNDAY NIGHT INTO MONDAY DIMINISHING INTO TUESDAY ...  
 
STRONG, DAMAGING WINDS. EXPECT IMPACTS OF DOWNED TREE LIMBS / TREES  
AS WELL AS POWER LINES. ANTICIPATE POWER OUTAGES. ROBUST SE CANADA  
STORM DEVELOPMENT WITH AN ACCOMPANYING PRESSURE RISE / FALL COUPLET  
OF ROUGHLY 2 MB / HR ACROSS S NEW ENGLAND (NOT AS STRONG AS FURTHER  
N BUT DECENT ENOUGH), COLD AIR ADVECTION PROCEEDS REARWARD YIELDING  
STEEP BOUNDARY LAYER LAPSE RATES (DRY-ADIABATIC) UP THROUGH H8, WITH  
55 TO 70 MPH W WINDS AT THE BOUNDARY LAYER TOP. SURFACE MOMENTUM  
TRANSFER, AT A MINIMUM, WIDESPREAD WIND ADVISORY HEADLINES, GUSTS  
EXCEEDING 45 MPH. NOT OUT OF THE QUESTION WE COULD SEE HIGH WIND  
WARNING CRITERIA ACROSS THE HIGH TERRAIN AND ALONG THE COASTLINE  
WITH GUSTS AROUND 60 MPH. HEIGHT OF WINDS AROUND MONDAY MORNING  
THAT'LL GRADUALLY DIMINISH INTO TUESDAY WHILE THE BOUNDARY REMAINS  
WELL-MIXED, YET SUBSIDING WITH INCREASING PRESENCE OF HIGH PRESSURE.  
 
WEDNESDAY ONWARD ...  
 
WATCHING ADDITIONAL ENERGY AND ASSOCIATED CONTINENTAL AIRMASSES THAT  
WILL ZIP ALONG A RATHER FLAT BASE OF A H5 TROF PERSISTING ACROSS S  
CANADA, BOWLED OVER THE N/NE CONUS. FAVORING THE EC, SOME LIGHT SNOW  
OUTCOMES POSSIBLE AT TIMES, OTHERWISE HIGH PRESSURE AND COLDER THAN  
AVERAGE CONDITIONS. FOCUS ON A FOLLOWING WEEKEND STORM SYSTEM THAT  
HAS BEEN CONSISTENTLY SIGNALED. LOW CONFIDENCE FORECAST, SIMPLY  
WATCH AND WAIT FOR NOW.  
 

 
   
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE.  
 
TONIGHT ...  
 
VFR, DRY WEATHER AND WINDS BECOMING CALM.  
 
SATURDAY ...  
 
VFR AND DRY WEATHER CONTINUES. LIGHT AND VARIABLE WINDS BECOMING  
LIGHT ONSHORE DURING THE AFTERNOON ALONG THE COAST.  
 
SATURDAY NIGHT ...  
 
VFR AND DRY WEATHER THRU THE EVENING, THEN MVFR AND PRECIP AFTER  
MIDNIGHT FROM WEST TO EAST. PTYPE, RAIN EXCEPT FREEZING RAIN  
ACROSS THE INTERIOR. LLWS LIKELY TOWARD 12Z SUNDAY MORNING ALONG  
THE SOUTH COAST INCLUDING CAPE COD AND ISLANDS.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...  
 
SUNDAY: MVFR/IFR CONDITIONS POSSIBLE. WINDY WITH AREAS OF GUSTS  
UP TO 30 KT. CHANCE RA, FZRA.  
 
SUNDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. STRONG  
WINDS WITH GUSTS UP TO 45 KT.  
 
MONDAY: VFR. STRONG WINDS WITH GUSTS UP TO 50 KT.  
 
MONDAY NIGHT: VFR. STRONG WINDS WITH GUSTS UP TO 45 KT.  
 
TUESDAY: VFR. WINDY WITH GUSTS UP TO 35 KT.  
 
TUESDAY NIGHT: VFR. WINDY WITH GUSTS UP TO 30 KT.  
 
WEDNESDAY: VFR. BREEZY.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SATURDAY NIGHT/...HIGH CONFIDENCE.  
 
HIGH PRESSURE TONIGHT AND SATURDAY YIELDS TRANQUIL WEATHER ON THE  
WATERS WITH LIGHT NNW WINDS TONIGHT BECOMING LOCALLY ONSHORE AND  
LIGHT SATURDAY.  
 
SATURDAY NIGHT EAST WINDS INCREASE TO 20-30 KT TOWARD SUNDAY  
MORNING AS LOW PRESSURE LIFTS NORTHEAST FROM NJ COAST. VSBY  
LOWERING IN RAIN TOWARD MORNING.  
 
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...  
 
SUNDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS  
UP TO 30 KT. ROUGH SEAS UP TO 10 FT. CHANCE OF RAIN. LOCAL  
VISIBILITY 1 TO 3 NM.  
 
SUNDAY NIGHT: LOW RISK FOR GALE FORCE WINDS WITH GUSTS UP TO  
45 KT. ROUGH SEAS UP TO 15 FT.  
 
MONDAY: MODERATE RISK FOR STORM FORCE WINDS WITH GUSTS UP TO  
50 KT. ROUGH SEAS UP TO 16 FT.  
 
MONDAY NIGHT: MODERATE RISK FOR GALE FORCE WINDS WITH GUSTS UP  
TO 45 KT. ROUGH SEAS UP TO 14 FT. CHANCE OF FREEZING SPRAY.  
 
TUESDAY: MODERATE RISK FOR GALE FORCE WINDS WITH GUSTS UP TO  
35 KT. ROUGH SEAS UP TO 11 FT. CHANCE OF FREEZING SPRAY.  
 
TUESDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS  
WITH GUSTS UP TO 30 KT. LOCAL ROUGH SEAS. CHANCE OF FREEZING  
SPRAY, SLIGHT CHANCE OF SNOW.  
 
WEDNESDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS  
UP TO 25 KT. SEAS LOCALLY APPROACHING 5 FT. CHANCE OF FREEZING  
SPRAY.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...GALE WATCH FROM SUNDAY EVENING THROUGH TUESDAY MORNING FOR  
ANZ230>237-251-255-256.  
GALE WATCH FROM SUNDAY AFTERNOON THROUGH TUESDAY MORNING FOR  
ANZ250-254.  
 

 
 

 
SYNOPSIS...NOCERA/SIPPRELL  
NEAR TERM...NOCERA  
SHORT TERM...NOCERA  
LONG TERM...SIPPRELL  
AVIATION...NOCERA/SIPPRELL  
MARINE...NOCERA/SIPPRELL  
 
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