482  
FXUS61 KBOX 101832  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAUNTON MA  
132 PM EST WED JAN 10 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE MOVES EAST OF THE REGION TODAY AND TONIGHT  
BRINGING MILDER WEATHER ON THURSDAY. UNSEASONABLY MILD  
TEMPERATURES ARE ANTICIPATED FRIDAY INTO FRIDAY NIGHT ALONG WITH  
PERIODS OF HEAVY RAIN, GUSTY WINDS ALONG WITH THE POTENTIAL FOR  
SOME FLOODING. THE RAIN MAY END AS SOME ICE ACROSS THE INTERIOR  
ON SATURDAY IF THE MUCH COLDER AIR ARRIVES BEFORE THE  
PRECIPITATION ENDS. DRY AND VERY COLD WEATHER IS FAVORED SUNDAY  
INTO MONDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
LARGE HIGH PRESSURE WILL CONTINUE TO MOVE EAST OF OUR REGION  
TODAY. LIGHT AND VARIABLE WINDS WILL EVENTUALLY BECOME LIGHT  
SOUTH WINDS BY LATE TODAY.  
 
ONLY MINOR TWEAKS TO THE FORECAST EARLY THIS AFTERNOON TO  
REFLECT OBSERVED TRENDS.  
 
STRONG WARM AIR ADVECTION IN THE LOWER LEVEL BEGINS IN EARNEST  
TONIGHT. INCREASING CLOUDS MID AND HIGH LEVEL CLOUDS, ESPECIALLY  
ACROSS THE WESTERN TWO-THIRDS OF SOUTHERN NEW ENGLAND. WITH 925  
MB WINDS EXPECTED TO INCREASE TO 35-45 KT TOWARD MIDNIGHT,  
EXPECTING MINIMUM TEMPERATURES TO BE RATHER EARLY TONIGHT, THEN  
REMAIN NEARLY STEADY OR SLOWLY RISE AFTER MIDNIGHT. MINIMUM  
TEMPERATURES CURRENTLY FORECAST TO BE ABOUT 10 DEGREES ABOVE  
NORMAL.  
 
THE OTHER ISSUE WITH THE STRONG WARM AIR ADVECTION WILL BE THE  
POSSIBILITY FOR SOME OVERRUNNING PRECIPITATION THIS EVENING AND  
OVERNIGHT. THERE IS A WINDOW THIS EVENING TOWARDS NW MA FOR  
PERIOD OF SPOTTY FREEZING DRIZZLE. THE MAJORITY OF THE FORCING  
AND DEEPER MOISTURE APPEAR TO BE JUST TO THE NW OF OUR AREA.  
THINKING COVERAGE IS NOT GOING TO BE WIDESPREAD ENOUGH TO ISSUE  
A WINTER WEATHER ADVISORY AT THIS TIME.  
 

 
   
SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/
 
 
VERY MILD WEATHER BY MID JANUARY STANDARDS EXPECTED THURSDAY  
AND THURSDAY NIGHT, WITH READINGS AT LEAST 15 DEGREES ABOVE  
NORMAL THROUGH THIS PERIOD. EXPECTING CONTINUAL SNOWMELT DURING  
THIS TIME, WHICH WILL BEGIN TO SET THE STAGE FOR A FLOODING  
THREAT LATER THIS WEEK. AREAS OF FOG ALSO EXPECTED, SOME OF  
WHICH MAY BE FAIRLY DENSE, ESPECIALLY THURSDAY NIGHT.  
 
EXPECTING MAINLY DRY WEATHER THURSDAY, WITH AN INCREASING RISK  
FOR RAIN FROM WEST TO EAST THURSDAY NIGHT, ESPECIALLY FROM  
WORCESTER COUNTY AND RI, WEST.  
 

 
   
LONG TERM /FRIDAY THROUGH TUESDAY/
 
 
HIGHLIGHTS...  
 
* HEAVY RAIN YIELDS A FLOODING RISK FRI AND SAT.  
* RAPID FREEZING POSSIBLE LATE SAT.  
* A RETURN OF COLDER THAN NORMAL CONDITIONS EARLY NEXT WEEK.  
 
OVERVIEW AND MODEL PREFERENCES...  
A GRADUAL TRANSITION IN A SLIGHT POSITIVE NAO/AO REGIME AS  
SUBTROPICAL HIGH BEGINS TO FORM BLOCK IN THE W ATLANTIC,  
ALLOWING THE TROF OVER SOCAL PHASES WITH A WEAKER N STREAM WAVE,  
LEADING TO A DRAW OF TROPICAL MOISTURE AND HIGH LATENT HEAT  
THROUGH A MEAN SW-NE ORIENTED JET. TWO WAVES WILL TRAVERSE THE  
ATTENDANT SFC FRONT FRI AND SAT WHICH LOOKS TO LEAD TO PERIODS  
OF HEAVY RAINFALL. THEREAFTER, AS THE RIDGE CONTINUES TO FORM A  
BLOCK OFFSHORE, THE LONGWAVE WILL PHASE WITH ARCTIC WAVE AND  
ALLOW ANOTHER ROUND OF ARCTIC AIR TO FOLLOW THE WET/UNSETTLED  
PERIOD. 10.00Z MODEL GUIDANCE SUITE CONTINUES TO SHOW GENERALLY  
GOOD SYNOPTIC SCALE AGREEMENT THROUGH THE WEEKEND. WHILE THERE  
CONTINUES TO BE MESO-SCALE AND THERMAL PROFILE DISAGREEMENTS,  
THESE WILL SLOWLY BECOME RESOLVED NOW THAT THE INITIATING WAVE  
(THE CUTOFF CURRENTLY IMPACTING SOCAL) IS ONSHORE AND BEING  
BETTER SAMPLED. GIVEN THE AGREEMENT AT THIS LEVEL, WILL CONTINUE  
TO LEAN MOST HEAVILY ON ENSEMBLES. THIS IS MAINLY DUE TO THE  
ANOMALOUS TROPICAL MOISTURE EVENT EXPECTED DURING THIS PERIOD,  
AND THE LOW RISK FOR THE INFLUENCE OF LOW LVL COLD AIR ON SAT  
(SOMETHING THAT AT LEAST A FEW MEMBERS REFLECT).  
 
DETAILS...  
 
FRI... DEEPENING LONGWAVE REACHES THE GULF OF MEXICO, ALLOWING  
THE ADVECTION OF HIGH PWAT AIR (NEARLY 1.5 INCHES, WHICH IS  
ALMOST 5 STD DEVIATIONS ABOVE JANUARY NORMALS) TOWARD NEW  
ENGLAND. WHILE THE FIRST IN A SERIES OF FRONTAL WAVES MOVING  
ALONG A SLOW MOVING BAROCLINIC ZONE TO THE NW IS EXPECTED TO  
SHIFT THROUGH THE GREAT LAKES INTO QUEBEC, A 60+ KT LLJ WITH  
STRONG FRONT END CONVERGENCE WILL YIELD A PERIOD OF MOD-HEAVY  
RAIN EARLY FRI MORNING INTO THE DAYTIME ON FRI. THIS WILL BE THE  
SHORTER LIVED AND GENERALLY WEAKER OF THE TWO WAVES, BUT STILL,  
QPF VALUES COULD APPROACH 1.00-1.50 UNTIL DRY AIR FILTERS IN  
ALOFT, LEADING TO DIMINISHING RAINFALL RATES THROUGH THE LATE  
AFTERNOON AND EVENING. THIS IS IN ADVANCE OF STRONGER LATENT  
HEAT RELEASE UPSTREAM NEAR THE S TAIL OF THE APPALACHIANS WHICH  
WILL FORM A STRONGER FRONTAL WAVE MOVING THROUGH ON SAT. MORE ON  
THIS BELOW, ALONG WITH THE POTENTIAL IMPACTS OF HEAVY RAIN BOTH  
FRI AND SAT. TEMPS REMAIN MILD THANKS TO H92 TEMPS NEAR +10C,  
YIELDING HIGHS IN THE LOW-MID 50S.  
 
FRI NIGHT INTO SAT NIGHT...  
SECONDARY FRONTAL WAVE, THIS ONE ASSOCIATED WITH A NEARLY 70+  
LLJ (EVEN AS LOW AS H92) WILL PASS ALONG THE FRONT AS IT MOVES  
ACROSS S NEW ENGLAND. THE TIMING IS CRITICAL HERE, AS THIS LOW  
COULD ULTIMATELY PASS DIRECTLY OVER, TO THE W OR TO THE E OF NEW  
ENGLAND. ENSEMBLES STILL YIELD A LOT OF SPREAD AT THIS TIME,  
BUT THIS WILL NEED TO BE WATCHED. A W OR DIRECT TRACK WOULD  
ALLOW FOR HEAVIER RAIN WITH CONVECTIVE ELEMENTS AS K-VALUES  
SHIFT WELL ABOVE 30 AND CONDITIONALLY UNSTABLE SOUNDINGS YIELD  
MODEST MU CAPE. THESE TRACKS COULD ALSO BE THE MEANS BY WHICH  
SOME OF THE MOMENTUM FROM THIS STRONG LLJ IS ABLE TO MIX TO THE  
SFC, HOWEVER WITH SOME LINGERING SNOWPACK AND AN IMPLIED  
INVERSION ON SOUNDINGS, A LACK OF NEAR SFC MIXING MAY BE ABLE  
TO KEEP IT ALOFT. STILL SOMETHING TO WATCH. OTHERWISE, A FURTHER  
E TRACK COULD ALLOW FOR SHALLOW, NEAR SFC COLD AIR IN FAST  
ENOUGH (THANKS TO ISALLOBARIC NORTH AND NORTHWESTERLIES) BEFORE  
THE MAIN PRECIP SHIELD DISSIPATES, ALLOWING FOR SOME WINTRY MIX  
(MOST LIKELY FZRA) ACROSS THE INTERIOR. AS MENTIONED ABOVE,  
THESE ARE MESOSCALE FEATURES WHICH WILL GRADUALLY EVOLVE.  
 
IN ANY CASE, ANOTHER ROUND OF HEAVY RAIN IS LIKELY WITH  
CONVECTIVE THE HELP. THE HEAVY RAIN, WILL COMBINE WITH HIGH  
DWPTS TO YIELD SNOWMELT BEGINNING FRI AND CONTINUING ON SAT.  
WITH FULL QPF FROM BOTH WAVES YIELDING A POTENTIAL BETWEEN  
1.50-4.00 INCHES (EVEN MORE IN SPECIFIC RUNS), THE ADDITIONAL  
SNOWMELT, COMBINED WITH A POTENTIAL FOR SNOW CLOGGED DRAINS  
COULD YIELD SOME URBAN AND POOR DRAINAGE FLOODING, AS WELL AS  
SOME FLOODING SPECIFICALLY IN FLASHIER SMALL STREAMS.  
 
FOLLOWING THE FLOODING RISK, THE INFLUENCE OF COLD AIR TIMING  
WILL BE IMPORTANT, AS A FREEZE IS POSSIBLE IMMEDIATELY FOLLOWING  
HEAVY RAIN. OVERNIGHT MINS ARE LIKELY TO DIP BELOW FREEZING  
BEFORE SUN MORNING.  
 
SUN...  
AS LOW PRES SHIFTS INTO THE MARITIMES, COLDER AIR BEGINS TO  
FILTER IN FROM THE W, ALTHOUGH ARCTIC HIGH PRES REMAINS ACROSS  
THE GREAT LAKES. TEMPS ALOFT, NEARLY ISOTHERMAL THROUGH H85,  
HOVER BETWEEN -10C AND -12C. THIS IS NEAR THE STANDARD FOR MID  
JANUARY, SO EXPECT HIGHS SUN TO REMAIN NEAR SEASONAL NORMALS,  
BUT COLDER THAN PREVIOUS 48 HOURS. SUN NIGHT MINS HOWEVER WILL  
BE DEPENDENT ON CENTER OF HIGH PRES, BUT THERE IS A POSSIBILITY  
FOR RADIATIONAL COOLING, WITH LOWS IN THE SINGLE DIGITS OR LOW  
TEENS.  
 
EARLY NEXT WEEK...  
ARCTIC INFLUENCED AIRMASS REMAINS IN PLACE WITH HIGH PRES  
ESPECIALLY THROUGH TUE. HOWEVER, WILL NEED TO WATCH WAVES  
ROTATING THROUGH THE LONGWAVE TROF, WHICH COULD BRING ABOUT A  
SNOWFALL EVENT. CONFIDENCE IS LOW IN TIMING OR DETAILS AT THIS  
TIME.  
 

 
   
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH THURSDAY NIGHT/...  
 
THROUGH 00Z...HIGH CONFIDENCE. VFR. LIGHT WINDS SLOWLY VEER TO  
THE SSW.  
 
TONIGHT...HIGH CONFIDENCE. MAINLY VFR CONDITIONS. LOW RISK FOR  
A BRIEF PERIOD OF SPOTTY LIGHT FREEZING RAIN ACROSS NORTHWEST  
MA.  
 
THURSDAY...MODERATE CONFIDENCE. TIMING UNCERTAIN BUT THREAT FOR  
MVFR TO IFR CONDITIONS WILL INCREASE MAINLY ACROSS THE INTERIOR  
DURING THE AFTERNOON AND ESPECIALLY EARLY EVENING.  
 
THURSDAY NIGHT...MODERATE CONFIDENCE. MVFR/IFR CONDITIONS  
EXPECTED. BREEZY. RA WITH AREAS BR. WIDESPREAD LLWS LIKELY.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /FRIDAY THROUGH SUNDAY/...  
 
FRIDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. WINDY WITH GUSTS  
TO 35 KT. RA.  
 
FRIDAY NIGHT: MAINLY IFR, WITH AREAS MVFR POSSIBLE. WINDY WITH  
LOCAL GUSTS TO 30 KT. RA, PATCHY BR.  
 
SATURDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. WINDY WITH  
GUSTS TO 35 KT. RA, SLIGHT CHANCE FZRA.  
 
SATURDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY.  
SLIGHT CHANCE SHRA.  
 
SUNDAY: VFR.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH THURSDAY NIGHT/...  
 
INCREASING S TO SW WINDS LATER TONIGHT THROUGH THURSDAY NIGHT.  
EXPECTING WINDS TO REMAIN MAINLY BELOW 25 KT. SOME OF THE WATERS  
EAST OF MA MAY SEE LOCAL GUSTS UP TO 25 KT. MAY NEED A SMALL  
CRAFT ADVISORY FOR SOME OF THE WATERS SOMETIME DURING THIS  
PERIOD. STILL EVALUATING.  
 
INCREASING RISK FOR RAIN FROM W TO E THURSDAY NIGHT.  
 
OUTLOOK /FRIDAY THROUGH SUNDAY/...  
 
FRIDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH LOCAL  
GUSTS UP TO 30 KT. AREAS OF ROUGH SEAS. RAIN.  
 
FRIDAY NIGHT: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 13 FT.  
RAIN.  
 
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP  
TO 30 KT. ROUGH SEAS UP TO 13 FT. RAIN.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 11 FT.  
SLIGHT CHANCE OF RAIN SHOWERS.  
 
SUNDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...NONE.  
 

 
 

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