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FXUS61 KBOX 181129  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
729 AM EDT THU APR 18 2019  
   
SYNOPSIS
 
 
AN APPROACHING WARM FRONT WILL BRING A FEW SHOWERS TODAY,  
ESPECIALLY IN THE AFTERNOON. THE WARM FRONT LIFTS TO THE NORTH  
TONIGHT INTO FRIDAY FOLLOWED BY WARMER AND MORE HUMID  
CONDITIONS ALONG WITH PATCHY LIGHT RAIN AND DRIZZLE AT TIMES.  
A PERIOD OF HEAVY RAINFALL IS POSSIBLE LATE FRIDAY NIGHT INTO  
SATURDAY NIGHT AS SLOW MOVING LOW PRESSURE APPROACHES FROM THE  
WEST. THE LOW PRESSURE MOVES ACROSS NEW ENGLAND SUNDAY. OFF AND  
ON RAIN CHANCES CONTINUE THROUGH TUESDAY, THEN EXPECTING DRIER  
CONDITIONS DURING THE MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
730 PM UPDATE...  
 
AS EXPECTED SHOWERS HAVE BROKEN UP AND WEAKENED AS THEY MOVED  
EAST INTO THE DRIER LOW LEVEL AIRMASS. SEVERAL SPOTS MANAGED TO  
GET SOME SPRINKLES/LIGHT RAIN OUT OF IT. NOT EXPECTING ANYTHING  
APPRECIABLE THIS MORNING...BETTER CHANCE BY THE AFTERNOON.  
SATELLITE SHOWS THE LEADING EDGE OF CLOUDS JUST CROSSING THE MA  
EAST COAST...THE OUTER CAPE WILL BE THE LAST TO ENJOY SUNSHIRE  
FOR ANOTHER HOUR OR SO BEFORE CLOUDING OVER FOR THE NEXT SEVERAL  
DAYS.  
 
PREVIOUS DISCUSSION...  
 
A BATCH OF SHOWERS AHEAD OF A WARM FRONT  
IS MOVING INTO WESTERN NEW ENG EARLY THIS MORNING. THE SHOWERS  
SHOULD WEAKEN AS THEY MOVE EAST THROUGH DAYBREAK AS LOW LEVELS  
ARE DRY, WITH JUST A BRIEF SHOWER OR SPRINKLE POSSIBLE.  
OTHERWISE, EXPECT MAINLY DRY CONDITIONS THIS MORNING WITH  
INCREASING RISK OF SCATTERED SHOWERS DEVELOPING IN THE AFTERNOON  
AS HIGHER THETA-E AIR AND MARGINAL ELEVATED INSTABILITY MOVES  
IN ALONG A STRENGTHENING LOW LEVEL JET.  
 
THE WARM FRONT SHOULD REMAIN JUST SOUTH AND WEST OF THE REGION  
THROUGH TODAY WITH SNE REMAINING IN THE COOLER AIR WITH LOTS OF  
CLOUDS. EXPECTED HIGHS WILL BE MOSTLY IN THE LOWER 50S WITH SOME  
UPPER 40S IN THE HIGHER TERRAIN. GUSTY S/SE WINDS WILL DEVELOP  
THIS AFTERNOON AS THE LOW LEVEL JET MOVES INTO THE REGION, WITH  
S/SE GUSTS 20-30 MPH AT TIMES.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/
 
 
TONIGHT...  
 
ANY SHOWER ACTIVITY EXPECTED TO LIFT TO THE NORTH BY EVENING.  
MID LEVEL TROUGH AMPLIFIES ACROSS THE MS VALLEY WITH DOWNSTREAM  
RIDGING BUILDING JUST EAST OF NEW ENG. DRIER AIR IN THE COLUMN  
LIFTS NORTH ACROSS THE REGION DURING THE NIGHT AS ABUNDANT LOW  
LEVEL MOISTURE PERSISTS. IN FACT, VERY DRY AIR IN THE MID LEVELS  
MOVE INTO THE REGION AFTER MIDNIGHT. THIS WILL RESULT IN AREAS  
OF LOW CLOUDS AND PATCHY DRIZZLE/LIGHT RAIN DEVELOPING AS THE  
WARM FRONT LIFTS NORTH ACROSS THE REGION. GIVEN THE DRY AIR  
ALOFT, PRECIP WILL LIKELY BE MORE DRIZZLE THAN SHOWERS. RISING  
TEMPS OVERNIGHT THROUGH THE 50S AFTER THE WARM FROPA. LOW LEVEL  
JET REMAINS ACROSS SE NEW ENG BUT INVERTED TEMP PROFILE SHOULD  
PREVENT KEEP STRONGER WINDS FROM MIXING DOWN TO THE GROUND.  
 
FRIDAY...  
 
HIGH AMPLITUDE TROUGH AND DEVELOPING CLOSED LOW OVER TN VALLEY  
SLOWLY MOVES EAST, BUT REMAINS WELL WEST OF SNE THROUGH THE DAY.  
THE PRONOUNCED DRY AIR ALOFT OVER NEW ENG WILL CONTINUE WITH  
LOTS OF LOW LEVEL MOISTURE LEADING TO MORE PATCHY DRIZZLE AT  
TIMES. DEEPER MOISTURE AND STRONG FORCING FOR ASCENT WILL BE  
FOCUSED ALONG A BOUNDARY WELL NORTH AND WEST OF SNE WHERE  
HEAVIER SHOWERS WILL BE FOCUSED. SOME OF THESE SHOWERS MAY  
REACH FAR WESTERN NEW ENG TOWARD EVENING AS THE DEEPER  
MOISTURE APPROACHES. SNE IN WARM SECTOR WITH TEMPS RISING WELL  
INTO THE 60S, WITH LOWER 70S IN THE MERRIMACK VALLEY AND NE MA,  
BUT COOLER ALONG THE IMMEDIATE SOUTH COAST. THE AIRMASS WILL  
HAVE A HUMID FEEL AS DEWPOINTS CLIMB WELL INTO THE 50S TO NEAR  
60.  
 
GUSTY SW WINDS EXPECTED AS THE LOW LEVEL JET PERSISTS AND THE  
WARMER AIR WILL ALLOW FOR INCREASED MIXING IN THE SHALLOW  
BOUNDARY LAYER. SW GUSTS TO 25-35 MPH WILL BE POSSIBLE AT  
TIMES.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
 
 
HIGHLIGHTS...  
 
* SHOWERS AT TIMES FRIDAY NIGHT THROUGH SUNDAY WITH HEAVY RAIN  
POTENTIAL FRI NIGHT AND SAT  
* DRIER BUT LINGERING SHOWER CHANCES NEXT WEEK  
 
FRIDAY NIGHT THROUGH SUNDAY...  
 
FRIDAY NIGHT BETTER MOISTURE MOVES IN AND WE MOVE INTO A 24-36 HOUR  
PERIOD OF MORE WIDESPREAD, LOCALLY HEAVY RAIN. THE BIG PICTURE  
PERSPECTIVE SHOWS RIDGING OVER THE INTERMOUNTAIN WEST AND A  
DEEP, BOWLING BALL LOW FORMING OVER THE TN VALLEY AT THE MID  
LEVELS. THIS AMPLIFYING TROUGH WILL KEEP THE CUTOFF LOW OUT OF  
THE BEST STEERING FLOW, LETTING IT TO LANGUISH OVER THE EAST  
COAST THROUGH EARLY SUNDAY BEFORE FINALLY LIFTING OUT. AT THE  
SURFACE WE SEE A SIMILAR EVOLUTION. SURFACE LOW CENTER LIFTS  
INTO SOUTHERN QC BY SATURDAY NIGHT BRINGING A WEAKENING COLD  
FRONT THROUGH SNE ON SUNDAY.  
 
BEING THAT WE'LL BE ON THE EAST SIDE OF THIS TROUGH FOR AN EXTENDED  
PERIOD, WE'LL BE ON THE RECEIVING END OF PROLONGED WIDESPREAD RAIN  
AS MENTIONED PREVIOUSLY. A FIRE HOSE OF MOISTURE (PWATS OVER 1.5", 2-  
3 SD ABOVE NORMAL FOR LATE APRIL) STRETCHES ALL THE WAY FROM THE  
TROPICS TO SOUTHERN NEW ENGLAND THROUGH EARLY SUNDAY. THIS MOISTURE  
TRANSPORT COMES COURTESY OF A ROBUST AND PERSISTENT 50-60KT 925MB  
LLJ. THIS TRAJECTORY COULD BRING HEAVY BANDS OF TRAINING PRECIP TO  
PORTIONS OF SOUTHERN NEW ENGLAND LATE FRIDAY THROUGH SATURDAY. THERE  
IS STILL CONSIDERABLE UNCERTAINTY WHERE EXACTLY THE HEAVIEST BANDS  
WILL SET UP, BUT THE BEST CHANCE OF THE GREATEST RAINFALL TOTALS  
LOOKS TO BE OVER WESTERN AND CENTRAL MA/CT. BY SUNDAY NIGHT MOST  
LOCATIONS WILL HAVE RECEIVED 1-2" OF RAIN, WITH LOCALLY HIGHER  
AMOUNTS LIKELY. THIS RAIN WILL EXACERBATE FLOODING ISSUES ON THE CT  
RIVER AND COULD CAUSE SOME URBAN AND POOR DRAINAGE FLOODING AS WELL.  
AS THE MID LEVEL LOW MOVES OVERHEAD SUNDAY THE SWATH OF HIGHEST  
PWATS MOVES EAST AND DRIER AIR MOVES OVERHEAD. OVERALL, SATURDAY  
LOOKS LIKE MORE OF A WASHOUT WHILE SUNDAY SHOWERS BECOME MORE  
SCATTERED, BUT CLOUDS AND RAIN ARE LIKELY TO STICK AROUND.  
 
STRONG 50-60 KT LLJ AT 925MB PREVIOUSLY MENTIONED WILL BRING GUSTY  
SOUTH/SOUTHWEST WINDS FRIDAY NIGHT AND SATURDAY, SLOWLY TAPERING OFF  
SATURDAY NIGHT AS THE JET MOVES OFFSHORE. FORTUNATELY MODEL  
SOUNDINGS INDICATE A PROFILE INVERTED ENOUGH TO KEEP THE WORST OF  
THE WINDS ALOFT. WIND GUSTS OF 35 MPH ARE POSSIBLE, WITH THE BEST  
CHANCE FOR THESE OR LOCALLY HIGHER GUSTS BEING ALONG THE SOUTH COAST  
AND IN THE HIGH ELEVATIONS OF WESTERN MA/CT.  
 
FINALLY, THIS PROLONGED SOUTHERLY FLOW WILL MEAN VERY MILD  
TEMPERATURES, WITH HIGH TEMPERATURES IN THE MID TO UPPER 60S  
SATURDAY AND SUNDAY. MOST NOTICEABLE, THOUGH, WILL BE THE EXTREMELY  
WARM LOW TEMPERATURES, ESPECIALLY FRIDAY NIGHT. AN INFLUX OF 50-60F  
DEWPOINTS WILL KEEP LOWS FROM DROPPING OUT OF THE LOW 60S OR UPPER  
50S FRIDAY NIGHT.  
 
MINOR COASTAL FLOODING MAY BE AN ISSUE DURING THE FRIDAY NIGHT HIGH  
TIDE ALONG THE SOUTH COAST, WITH PROLONGED STRONG SOUTHERLY WINDS.  
IMPACT SEEMS LOW AT THE MOMENT. SEE COASTAL FLOOD SECTION FOR  
DETAILS.  
 
MONDAY THROUGH WEDNESDAY...  
 
LOWER CONFIDENCE IN DETAILS FOR THE FIRST HALF OF NEXT WEEK, BUT THE  
FLOW BECOMES MORE PROGRESSIVE AND ZONAL BEHIND OUR DEPARTING LOW.  
THE FORECAST CONTINUES TO INDICATE A DRYING TREND COMPARED TO THE  
WEEKEND, BUT CURRENT RUNS OF THE EC WANT TO SPIN UP ANOTHER COASTAL  
LOW EARLY MONDAY WHICH WOULD THROW A WRENCH IN THE DRY WEATHER  
PLANS, WHILE THE GFS BUILDS IN A HIGH. WILL STICK WITH THE MORE  
CONSISTENT DRIER SOLUTION FOR NOW. AGREEMENT IS BETTER THAT A COLD  
FRONT MOVES THROUGH AROUND TUESDAY/TUESDAY NIGHT BRINGING ANOTHER  
BRIEF SHOT OF SHOWERS INTO WEDNESDAY.  
 

 
   
AVIATION /12Z THURSDAY THROUGH MONDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY/...  
 
THROUGH 12Z...  
VFR. MID/HIGH CLOUDS WITH GRADUALLY LOWERING CIGS. A BRIEF  
SHOWER POSSIBLE ACROSS WESTERN MA/CT  
 
TODAY...HIGH CONFIDENCE.  
VFR CIGS THIS MORNING WILL LOWER TO MVFR FROM SW TO NE AFTER  
18Z. AREAS OF IFR AND PATCHY FOG POSSIBLE TOWARD EVENING.  
SCATTERED SHOWERS LIFTING NORTH ACROSS THE REGION THIS  
AFTERNOON. S/SE WIND GUSTS 20-25 KT DEVELOPING IN THE AFTERNOON.  
 
TONIGHT...MODERATE CONFIDENCE.  
WIDESPREAD MVFR/IFR CIGS WITH AREAS OF LIFR AND FOG POSSIBLE  
ALONG THE SOUTH COAST. PATCHY DRIZZLE. SW GUSTS TO 25 KT  
CAPE/ISLANDS. LLWS ALONG THE SOUTH COAST AND CAPE/ISLANDS WITH  
S/SW WINDS AROUND 50 KT AT 2K FT.  
 
FRIDAY...MODERATE CONFIDENCE.  
WIDESPREAD MVFR/IFR WITH PATCHY LIGHT RAIN/DRIZZLE. SW GUSTS TO  
35 KT POSSIBLE. CONTINUED LLWS ALONG THE SOUTH COAST AND  
CAPE/ISLANDS WITH S/SW WINDS 50-55 KT AT 2K FT.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TRENDS WITH CIGS LOWERING TO  
MVFR/IFR LATE TODAY AND TONIGHT.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TRENDS WITH CIGS LOWERING TO  
MVFR THIS AFTERNOON AND POSSIBLY IFR TONIGHT.  
 
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...  
 
FRIDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. WINDY WITH  
GUSTS UP TO 30 KT. SHRA.  
 
SATURDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. WINDY WITH  
GUSTS UP TO 30 KT. SHRA.  
 
SATURDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.  
CHANCE SHRA.  
 
SUNDAY: VFR. BREEZY. CHANCE SHRA.  
 
SUNDAY NIGHT: VFR. CHANCE SHRA.  
 
MONDAY: VFR. BREEZY. SLIGHT CHANCE SHRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE.  
 
A LOW LEVEL JET WILL MOVE ACROSS THE WATERS THIS AFTERNOON AND  
PERSIST THROUGH FRIDAY. S/SE GUSTS TO 25-30 KT DEVELOPING THIS  
AFTERNOON THEN BECOMING SW TONIGHT INTO FRIDAY. A FEW SHOWERS  
DEVELOPING THIS AFTERNOON. VSBYS BECOME POOR TONIGHT IN  
DEVELOPING FOG AND DRIZZLE, SLOWLY IMPROVING FRIDAY.  
 
OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...  
 
FRIDAY NIGHT: LOW RISK FOR GALE FORCE WINDS WITH GUSTS UP TO  
35 KT. ROUGH SEAS UP TO 12 FT. CHANCE OF RAIN SHOWERS.  
 
SATURDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. ROUGH SEAS UP TO 14 FT. RAIN SHOWERS LIKELY.  
 
SATURDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS  
WITH GUSTS UP TO 30 KT. ROUGH SEAS UP TO 14 FT. RAIN SHOWERS.  
 
SUNDAY: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 13 FT. CHANCE  
OF RAIN SHOWERS.  
 
SUNDAY NIGHT: WINDS LESS THAN 25 KT. ROUGH SEAS UP TO 10 FT.  
SLIGHT CHANCE OF RAIN SHOWERS.  
 
MONDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS.  
 

 
   
TIDES/COASTAL FLOODING
 
 
WITH THE STRONG SOUTHERLY WINDS ALIGNED WITH ASTRONOMICAL HIGH  
TIDES DUE TO THE FULL MOON LATE THIS WEEK, THERE IS A CHANCE FOR  
THAT A FEW LOCATIONS ALONG THE SOUTH COAST MAY SEE MINOR  
COASTAL FLOODING AROUND HIGH TIDE TONIGHT, BUT THERE IS A  
BETTER CHANCE FOR THE FRIDAY NIGHT HIGH TIDE. WILL MONITOR FOR  
POTENTIAL COASTAL FLOOD HEADLINES.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT FRIDAY FOR  
ANZ231>235-237-255-256.  
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS  
EVENING FOR ANZ230.  
SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING  
FOR ANZ236.  
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT  
FRIDAY FOR ANZ250-254.  
 

 
 

 
SYNOPSIS...KJC/BW  
NEAR TERM...KJC/BW  
SHORT TERM...KJC  
LONG TERM...BW  
AVIATION...KJC/BW  
MARINE...KJC/BW  
TIDES/COASTAL FLOODING...  
 
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