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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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