253  
FXUS61 KBOX 091200  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAUNTON MA  
700 AM EST TUE JAN 9 2018  
   
SYNOPSIS
 
 
LARGE HIGH PRESSURE WILL BRING DRY AND SEASONABLY COOL WEATHER  
TODAY AND WEDNESDAY. HIGH PRESSURE THEN MOVES OFF THE COAST  
ALLOWING FOR MODERATING TEMPERATURES THURSDAY AND WELL ABOVE  
NORMAL TEMPERATURES BY FRIDAY, DESPITE RAINY AND BREEZY WEATHER.  
UNSETTLED WEATHER MAY CONTINUE INTO SATURDAY AND SOME WINTRY  
PRECIPITATION IS EVEN POSSIBLE ACROSS THE INTERIOR DEPENDING ON  
HOW MUCH COLD AIR WORKS BACK INTO THE REGION. DRY AND COLD  
WEATHER ARE FAVORED SUNDAY INTO MONDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
7AM...  
TRICKY TO SPOT THE EXACT LOCATION OF THE VERY WEAK COLD FRONT  
MOVING THROUGH THIS MORNING AS THE MODIFIED AIRMASS FROM  
YESTERDAY, AND MILD AIR ON THE BACK SIDE OF THIS FRONT ARE  
NEARLY IDENTICAL. IN ANY CASE, THE PRIMARY IMPACT WILL BE FOR  
INCREASING W WINDS THIS MORNING AND AFTERNOON WITH TEMPS RISING  
ABOVE FREEZING FOR MORE OF S NEW ENGLAND. CURRENT FORECAST  
REFLECTS THESE THOUGHTS ALREADY SO NO MAJOR CHANGES WILL BE  
NECESSARY WITH THIS UPDATE. THE ONLY UPDATE WILL BE TO ADD A FEW  
LIGHT FLURRIES TO THE INTERIOR AS THE REMAINING MOISTURE  
ASSOCIATED WITH THE FRONT IS FORCED OUT.  
 
PREVIOUS DISCUSSION FOLLOWS...  
 
A COLD FRONT CROSSES THE REGION EARLY THIS MORNING...BUT WITH  
VERY DRY MID LEVELS NOT EXPECTING ANY PRECIPITATION. UNLIKE LAST  
WEEK, THE AIRMASS BEHIND THIS FRONT IS MORE OF PACIFIC ORIGIN  
SO HIGH TEMPS WILL ACTUALLY BE A FEW DEGREES ABOVE NORMAL. HIGH  
TEMPS WILL MAINLY BE IN THE UPPER 30S TO AROUND 40. SOME  
STRATO-CUMULUS EXPECTED BEHIND THIS FRONT WITH THE MAJORITY OF  
THAT ACROSS THE INTERIOR, WHILE MORE SUNSHINE EXPECTED ALONG THE  
COASTAL PLAIN. DECENT MIXING SHOULD RESULT IN WEST TO NORTHWEST  
WIND GUSTS OF 20 TO 30 MPH DEVELOPING LATER THIS MORNING AND  
AFTERNOON.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
 
 
TONIGHT...  
 
HIGH PRESSURE BUILDS IN FROM THE WEST ALLOWING WINDS TO DIMINISH  
THIS EVENING ALONG WITH MAINLY CLEAR SKIES. GIVEN THE DEEP  
SNOWPACK STILL IN PLACE ALONG WITH IDEAL RADIATIONAL COOLING  
CONDITIONS...MANY LOCATIONS SHOULD BOTTOM OUT IN THE SINGLE  
DIGITS TO MIDDLE TEENS. THE MILD SPOTS WILL BE THE URBAN HEAT  
ISLANDS OF DOWNTOWN BOSTON/PROVIDENCE WHERE LOW TEMPS SHOULD  
MAINLY BE IN THE UPPER TEENS TO THE LOWER 20S.  
 
WEDNESDAY...  
 
HIGH PRESSURE SLOWLY SLIDES EAST OF THE REGION. THIS WILL RESULT  
IN RATHER LIGHT WINDS AND PLENTY OF SUNSHINE...ALTHOUGH DO  
EXPECT SOME MID/HIGH LEVEL CLOUDINESS TO INCREASE FROM THE WEST  
DURING THE AFTERNOON. DESPITE WARMING MID LEVEL TEMPERATURES,  
THE LOW JANUARY SUN ANGLE AND WEAK MIXING SHOULD HOLD AFTERNOON  
HIGH TEMPERATURES IN THE 30S.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
 
 
HIGHLIGHTS...  
 
* MILDER LATE WEEK.  
* SOME HEAVY RAINFALL POSSIBLE FRI AND SAT.  
* LOW RISK FOR WINTRY PRECIP INTERIOR SAT.  
 
OVERVIEW AND MODEL PREFERENCES...  
A SHIFTING PATTERN WILL LEAD TO A 48+ HR PERIOD OF MILD BUT  
UNSETTLED CONDITIONS LAT THIS WEEK AND THE WEEKEND, BEFORE  
ANOTHER ROUND OF ARCTIC INFLUENCED AIR MOVES IN AGAIN EARLY NEXT  
WEEK. THE NEAR NEUTRAL AO/NAO WILL ALLOW A BERMUDA HIGH AND  
ATTENDANT RIDGING TO BUILD JUST OFF THE E CONUS AS S AND N  
STREAM WAVES SHOW SOME SIGN OF PHASING IN THE LEE OF THE ROCKIES  
LATE WEEK. THIS SHIFTS THE FLOW TO MORE SW-NE ORIENTATION  
ACROSS THE NE, TAPS GULF OF MEXICO MOISTURE AND LEADS TO MILD  
CONDITIONS. THE MEAN SW-NE JET IS REPRESENTED AS A SLOW MOVING  
FRONT, WITH AT LEAST 2 PREDOMINANT FRONTAL WAVES (THE FIRST  
MOVES NW OF THE REGION FRI, WHILE THE SECOND WILL PASS VERY NEAR  
OR OVER NEW ENGLAND ON SAT. ALTHOUGH WARM OVERALL, THE  
TRAJECTORY OF THE LOW COULD INTRODUCE SOME LOWER LVL COLD AIR  
FOR INTERIOR PORTIONS OF THE FORECAST AREA. THE THERMAL PROFILES  
AND LOW PRES TRACK WILL GRADUALLY BECOME MORE APPARENT  
ESPECIALLY AS THE S STREAM WAVES MOVES ONSHORE FROM CALIFORNIA  
AND BECOMES BETTER SAMPLED. HOWEVER, AM NOTICING ENOUGH SYNOPTIC  
AGREEMENT TO BASELINE THE FORECAST WITH A BLEND OF AVAILABLE  
GUIDANCE, BUT WITH A BIT MORE WEIGHT ON CURRENT ENSEMBLES, AS  
THESE WILL TAKE INTO ACCOUNT ALL POTENTIAL SOLUTIONS WITHIN THE  
ENVELOPE.  
 
DETAILS...  
 
WED NIGHT...  
SOUNDINGS STILL SUPPORT A FAIRLY ROBUST INVERSION WED IN SPITE  
OF WARMING BETWEEN H8 AND H92 WARMING TO AN AVERAGE OF NEARLY  
+7C. INITIALLY, WITH HIGH PRES IN PLACE, (OUTSIDE OF A FEW  
CLOUDS) CONDITIONS SUPPORT SOME RADIATIONAL COOLING WHICH WILL  
ALLOW TEMPS TO DROP INTO THE MID AND UPPER 20S. BY EARLY AM,  
WITH CONTINUED LOW LVL MOISTURE INCREASE, AND DRYING ALOFT WITH  
CONTINUED SUBSIDENCE, MAY NEED TO WATCH FOR PATCHY LIGHT  
FREEZING DRIZZLE OR ICING DUE TO CONDENSATION. THIS IS VERY  
MESOSCALE, BUT SOMETHING TO WATCH OVER THE NEXT 24-36 HOURS.  
 
THU...  
CONTINUED WARMING THROUGH THE COLUMN AS H92/H8 TEMPS APPROACH  
+10C BY THU AFTERNOON. RETURN FLOW INCREASES, WITH BREEZY S-SW  
FLOW. MID LVL CLOUDS LIKELY AS THE COLUMN CONTINUES TO FULLY  
MOISTEN. LOW RISK FOR A SHRA, BUT GIVEN HIGH PRES REMAINS THE  
DOMINANT PLAYER, THESE ARE LIKELY TO BE FEW AND FAR BETWEEN ON  
THU. HIGHS APPROACH 50F.  
 
THU NIGHT INTO FRI...  
FIRST ROUND OF LOW PRES SHIFTS INT QC ALLOWING 40-50KT LLJ TO  
SLIDE TOWARD NEW ENGLAND ASSOCIATED WITH PWATS NEAR 5 STD  
DEVIATIONS ABOVE NORMAL. THIS WILL YIELD A ROUND OF MOD-HEAVY  
RAINFALL BEGINNING LATE THU AND AND CONTINUING INTO FRI AS THIS  
FIRST WAVE SHIFTS NNE. WITH INCREASING DWPTS (TO NEAR 50F),  
AMBIENT TEMPS IN THE LOW 50S, MOD-HEAVY RAIN, WILL LIKELY SEE A  
FAIR AMOUNT OF SNOW MELT TO ACCOMPANY THIS RAINFALL. THEREFORE,  
AGREE WITH PREVIOUS ASSESSMENT OF A RISK FOR URBAN AND POOR  
DRAINAGE FLOODING, ESPECIALLY AS SNOWFALL COULD CLOG SOME AREA  
DRAINS.  
 
FRI NIGHT INTO SAT...  
SECONDARY FRONTAL WAVE, AND WHAT LOOKS LIKE THE STRONGER OF THE  
TWO WILL SLIDE ALONG THE E SHIFTING FRONT. STILL SOME  
DISAGREEMENT ON WHETHER THIS WAVE PASSES DIRECTLY OVER OR JUST  
NEAR S NEW ENGLAND, BUT THE PATTERN SUPPORTS A MAINLY WARM  
SOLUTION. AT ODDS WOULD BE THE INTERIOR, WHICH COULD SEE A DRAW  
OF COLDER AIR SAT AND SEE A WINTRY CHANGE-OVER. AS MENTIONED  
ABOVE, THERMAL PROFILES WILL BECOME BETTER DEFINED WITH TIME.  
LLJ INCREASES TO 60+ KT (NEARLY 3 STD DEVIATIONS ABOVE NORMAL)  
AND PWATS REMAIN ELEVATED. THEREFORE, EXPECT ANOTHER ROUND OF  
MOD-HEAVY RAINFALL WHERE THE CHANGE DOES NOT OCCUR. IN FACT QPF  
ENSEMBLE PROBS ARE ALREADY BETWEEN 70 AND 90 PERCENT FOR 1.00+  
INCH TOTALS, WITH EVEN SOME LOW PROBS OF 2.00+. FOCUS LOOKS TO  
BE MAINLY ACROSS S COASTAL MA/RI, AS THIS IS WHERE BEST LLJ  
CONVERGENCE IS CURRENTLY PROGGED, BUT WITH HIGH K-VALUES AND  
SOME IMPLIED CONDITIONAL INSTABILITY, HEAVY RAIN IS POSSIBLE  
EVERYWHERE. THEREFORE, WILL CONTINUE TO HIGHLIGHT THE RISK FOR  
URBAN/POOR DRAINAGE FLOODING WITH SNOWMELT/CLOGGING DRAINS.  
 
SUN INTO EARLY NEXT WEEK...  
THE LONGWAVE TROF WHICH BRINGS ABOUT THE WET AND UNSETTLED  
CONDITIONS FOR LATE WEEK LOOK TO PHASE SOMEWHAT WITH A TROF  
ASSOCIATED WITH A BAFFIN ISLAND VORTEX. THIS WILL INTRODUCE  
ANOTHER ROUND OF ARCTIC AIR. AVERAGE H92 TEMPS DROP BACK TO  
ABOUT -15C, SO ANOTHER ROUND OF TEMPS GENERALLY BELOW NORMAL ARE  
LIKELY. HIGH PRES AT THE SFC SUGGESTS MAINLY DRY CONDITIONS.  
 

 
   
AVIATION /11Z TUESDAY THROUGH SATURDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY/...  
 
TODAY...HIGH CONFIDENCE.  
REMNANT LOWER VFR CLOUDS WILL TREND TOWARD SCT THIS MORNING  
ESPECIALLY E OF THE CT VALLEY. OTHERWISE, WINDS SHIFT FROM SW TO  
MAINLY W, WITH GUSTS 20-30 KT THROUGH THE EVENING.  
 
TONIGHT AND WEDNESDAY...HIGH CONFIDENCE. VFR CONDITIONS AS WINDS  
DIMINISH THIS EVENING.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...  
 
WEDNESDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.  
SLIGHT CHANCE FZDZ IN THE INTERIOR.  
 
THURSDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. SLIGHT  
CHANCE FZRA, SLIGHT CHANCE FZDZ.  
 
THURSDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. RA,  
PATCHY BR.  
 
FRIDAY: MVFR/IFR CONDITIONS POSSIBLE. WINDY WITH GUSTS TO  
35 KT. RA, PATCHY BR.  
 
FRIDAY NIGHT: MAINLY IFR, WITH LOCAL MVFR POSSIBLE. BREEZY. RA,  
FZRA, PATCHY BR.  
 
SATURDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. WINDY WITH  
GUSTS TO 30 KT. RA LIKELY, CHANCE FZRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY/...  
 
TODAY...HIGH CONFIDENCE. COLD FRONT CROSSES THE WATERS EARLY  
THIS MORNING...RESULTING IN WNW WIND GUSTS OF 20 TO 30 KNOTS  
LATER THIS MORNING AND AFTERNOON.  
 
TONIGHT AND WEDNESDAY...HIGH CONFIDENCE. HIGH PRESSURE BUILDS IN  
FROM THE WEST TONIGHT ALLOWING WINDS/SEAS TO GRADUALLY DIMINISH  
BELOW SMALL CRAFT THRESHOLDS. BY DAYBREAK WEDNESDAY...WINDS/SEAS  
WILL HAVE DROPPED BELOW SMALL CRAFT THRESHOLDS ACROSS ALL  
WATERS.  
 
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...  
 
WEDNESDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. SEAS LOCALLY APPROACHING 5 FT.  
 
THURSDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.  
 
THURSDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS  
APPROACHING 5 FT. RAIN.  
 
FRIDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH LOCAL  
GUSTS UP TO 30 KT. ROUGH SEAS UP TO 10 FT. RAIN.  
 
FRIDAY NIGHT: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 13 FT.  
RAIN.  
 
SATURDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. ROUGH SEAS UP TO 13 FT. RAIN.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR  
ANZ231>235-237-251.  
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ230-  
236.  
SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR ANZ250-  
254>256.  
 

 
 

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