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FXUS61 KBOX 202346  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
646 PM EST MON JAN 20 2020  
   
SYNOPSIS
 
 
HIGH PRESSURE FROM THE MIDWEST WILL BUILD OVER SOUTHERN NEW  
ENGLAND FOR MOST OF THIS WEEK, BRINGING DRY WEATHER.  
TEMPERATURES WILL BE COLD TUESDAY, THEN MODERATE THE REST OF  
THIS WEEK. THERE IS THE POTENTIAL FOR A COASTAL STORM THIS  
WEEKEND, BUT UNCERTAINTY EXISTS IN REGARDS TO TIMING AND  
PRECIPITATION TYPES.  
 

 
   
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
 
 
MOST SIGNIFICANT CHANGE TO THE FORECAST THIS EVENING WAS TO  
LOWER DEW POINT TEMPERATURES THROUGH THIS EVENING TO REFLECT  
OBSERVED TRENDS. OTHERWISE, DRY WEATHER WITH CLEAR SKIES  
PREVAIL. WILL NEED TO WATCH TEMPERATURES CLOSELY, AS THEY COULD  
FALL LOWER THAN CURRENT FORECAST SHOULD THE NORTHWEST WIND  
DIMINISH TOO MUCH.  
 
PREVIOUS DISCUSSION...  
 
PRESSURE GRADIENT LEADING MIDWEST HIGH PRESSURE WILL BE  
DIMINISHING OVER SOUTHERN NEW ENGLAND TONIGHT, ALLOWING WINDS TO  
DIMINISH. THE HIGH WILL BRING SUFFICIENT SUBSIDENCE FOR CLEAR  
SKIES. UPPER FLOW REMAINS OUT OF THE NORTHWEST. DEW POINTS ARE  
CURRENTLY IN THE SINGLE NUMBERS AND BELOW ZERO. WITH CLEAR SKIES  
AND WINDS DIMINISHING THERE SHOULD BE ROOM FOR RADIATIONAL  
COOLING TO DEVELOP, ESPECIALLY IN WESTERN AND CENTRAL  
MA/NORTHERN CT. THIS POINTS TO MIN TEMPS IN THE SINGLE NUMBERS,  
AND POSSIBLY A LITTLE BELOW ZERO IN SPOTS.  
 

 
   
SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/
 
 
HIGH PRESSURE REMAINS IN CONTROL MUCH OF THE PERIOD. EXPECT FAIR  
WEATHER TUESDAY AND TUESDAY NIGHT. TEMPS ALOFT IN A SHALLOW  
MIXING REGIME SUPPORT MAX SFC TEMPS IN THE 20S, POSSIBLY A FEW  
LOW 30S, DURING THE DAY. NIGHTTIME TEMPS SHOULD REACH THE SINGLE  
NUMBERS AND TEENS.  
 
UPPER FLOW SHOWS A SHORTWAVE AND ASSOCIATED COLD POOL SWEEPING  
ACROSS NEW ENGLAND TUESDAY EVENING. MUCH OF THIS IS CONCENTRATED  
OVER NORTHERN NEW ENGLAND, BUT SOME OF THE COLD POOL AND  
MOISTURE REACHES SOUTH OF THE NH BORDER. THE BEST CHANCE OF  
CLOUDS WILL BE ALONG THE MA EAST COAST AND OVER THE EASTERN  
COASTAL WATERS AS THE COLD AIR MOVES OVER THE 4-6C WATER.  
 

 
   
LONG TERM /WEDNESDAY THROUGH MONDAY/
 
 
HIGHLIGHTS...  
 
* MODERATING TEMPERATURES BEGIN WED, WITH ABOVE NORMAL VALUES  
THU/FRI, ALONG WITH CONTINUED DRY WEATHER  
 
* POTENTIAL COASTAL STORM THIS WEEKEND WOULD FAVOR MORE RAIN  
THAN SNOW ALONG THE I-95 CORRIDOR, BUT UNCERTAIN ACROSS THE  
INTERIOR  
 
DETAILS...  
 
WEDNESDAY THROUGH FRIDAY...  
 
LARGE HIGH PRESSURE WILL REMAIN IN CONTROL DURING THIS TIME.  
THIS WILL MAINTAIN DRY/TRANQUIL WEATHER, BUT TEMPERATURES WILL  
MODERATE AS SOME UPPER LEVEL RIDGING BUILDS INTO SOUTHERN NEW  
ENGLAND. WEAK GRADIENT MAY ALLOW FOR SEA BREEZE DEVELOPMENT, SO  
COULD BE SOME COOLING ALONG THE VERY IMMEDIATE COAST DURING THE  
AFTERNOON. REGARDLESS, GIVEN LIGHT WINDS AND ABOVE NORMAL  
TEMPERATURES, IT WILL FEEL RATHER COMFORTABLE OUTSIDE DURING  
THU AND FRI AFTERNOONS BY LATE JANUARY STANDARDS.  
 
THIS WEEKEND...  
 
THE LATEST LONGER RANGE GUIDANCE CONTINUES TO DEPICT POTENTIAL  
FOR A COASTAL STORM SOMETIME SATURDAY NIGHT INTO SUNDAY NIGHT,  
POSSIBLY EVENING INTO MONDAY MORNING. CONSIDERABLE UNCERTAINTY  
REMAINS ON THE EXACT TRACK AND TIMING OF THE VARIOUS COMPONENTS  
OF THIS SYSTEM, WHICH IS NOT ALL THAT UNUSUAL THIS TIME OF  
YEAR. THERE IS RATHER HIGH CONFIDENCE WE WILL SEE A PERIOD OF  
MEASURABLE PRECIPITATION. CONFIDENCE IS MUCH LOWER ON THE  
TIMING AND PRECIPITATION TYPE DETAILS.  
 
TOOK A CONSENSUS/ENSEMBLE MEAN APPROACH TO SMOOTH OVER THE LESS  
PREDICTABLE DETAILS. THAT PATTERN SUGGEST MORE OF A RAIN/SNOW  
MIX ACROSS SOUTHERN NEW ENGLAND, INSTEAD OF A BIG SNOWSTORM FOR  
EVERYONE. SNOW MORE FAVORED ACROSS THE INTERIOR, ESPECIALLY AT  
NIGHT. BOTH OPTIONS REMAIN POSSIBILITIES, HOWEVER. THERE IS  
SOME BLOCKING EXPECTED TO OUR NORTH, SO THIS COULD BE A SLOW-  
MOVING COASTAL STORM. IT MAY BE MONDAY MORNING BEFORE THIS LOW  
PRESSURE MOVES OFFSHORE.  
 

 
   
AVIATION /00Z TUESDAY THROUGH SATURDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
TONIGHT...HIGH CONFIDENCE.  
 
VFR MOST AREAS. NW WINDS 10-15 KT DIMINISH THIS EVENING.  
 
TUESDAY AND TUESDAY NIGHT...HIGH CONFIDENCE.  
 
VFR. NORTHWEST WINDS LESS THAN 10 KT.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...  
 
WEDNESDAY THROUGH FRIDAY: VFR.  
 
FRIDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE.  
 
SATURDAY: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. CHANCE RA,  
SLIGHT CHANCE SN.  
 

 
   
MARINE
 
 
TONIGHT...NORTHWEST WIND DIMINISHES EARLY TONIGHT WITH WINDS  
10-15 KT MUCH OF THE NIGHT WITH POTENTIAL GUSTS TO 20 KT. SEAS  
UP TO 5 FEET ON THE OUTER WATERS SHOULD SUBSIDE BELOW 5 FEET BY  
MORNING. SMALL CRAFT ADVISORY HAVE BEEN ENDED NEAR THE SHORE  
BUT LINGER ON THE OUTER WATERS A WHILE LONGER.  
 
TUESDAY...NORTHWEST WINDS 10 KT OR LESS. SEAS LESS THAN 5 FEET.  
 
TUESDAY NIGHT...POSSIBLY A FEW SNOW SHOWERS OVER THE WATERS  
EARLY AT NIGHT. CONTINUED NORTHWEST WINDS 10 KT OR LESS AND SEAS  
LESS THAN 5 FEET.  
 
OUTLOOK /WEDNESDAY THROUGH SATURDAY/...  
 
WEDNESDAY THROUGH THURSDAY: WINDS LESS THAN 25 KT.  
 
THURSDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS  
APPROACHING 5 FT.  
 
FRIDAY: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS.  
 
FRIDAY NIGHT: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 9 FT.  
 
SATURDAY: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 9 FT. CHANCE  
OF RAIN.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ250-254-255.  
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ256.  
 

 
 

 
SYNOPSIS...WTB/BELK  
NEAR TERM...WTB/BELK  
SHORT TERM...WTB  
LONG TERM...BELK  
AVIATION...WTB/BELK  
MARINE...WTB/BELK  
 
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