397
FXUS61 KBOX 040821
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
421 AM EDT SAT JUL 4 2026
WHAT HAS CHANGED
THE EXTREME HEAT WARNING WAS REPLACED WITH A HEAT ADVISORY FOR
SOUTHERN NEW ENGLAND THROUGH 8 PM THIS EVENING.
KEY MESSAGES
- HOT AND HUMID TODAY WITH A FEW SHOWERS & T-STORMS THIS AFTERNOON
INTO TONIGHT...BUT NOT A WASHOUT. MAIN SEVERE WEATHER/DAMAGING
WIND GUST THREAT IS TO OUR SOUTHWEST WITH JUST A LOW RISK IN OUR
REGION WITH THE BEST CHANCE FOR THAT IN SOUTHWEST MA/CT.
- MUCH COOLER TEMPERATURES FOR THE FIRST HALF OF NEXT WEEK AND
THAT IS ESPECIALLY TRUE IF THE POTENTIAL FOR A SOAKING HEAVY
RAIN COMES TO FRUITION IN THE LATE SUN THROUGH TUE TIME FRAME.
DISCUSSION
KEY MESSAGE 1...HOT AND HUMID TODAY WITH A FEW SHOWERS & T-STORMS
THIS AFTERNOON INTO TONIGHT...BUT NOT A WASHOUT. MAIN SEVERE
WEATHER/DAMAGING WIND GUST THREAT IS TO OUR SOUTHWEST WITH JUST A
LOW RISK IN OUR REGION WITH THE BEST CHANCE FOR THAT IN SOUTHWEST MA
ONE MORE HOT AND HUMID DAY OF WEATHER IS ON TAP FOR SOUTHERN NEW
ENGLAND TODAY. HOWEVER...THE UPPER LEVEL RIDGE IS IN THE PROCESS OF
BREAKING DOWN WHICH WILL RESULT IN SOMEWHAT LOWER MID LEVEL
TEMPERATURES. SO WHILE WE WILL NOT SEE THE EXTREME HEAT OF THE PAST
TWO DAYS...STILL EXPECT HIGHS TO REACH THE MIDDLE 90S IN MANY
LOCATIONS. HEAT INDICES OF 95-102 ARE EXPECTED TODAY...SO NOT TO THE
EXTREME LEVELS OF THE PAST TWO DAYS. NONETHELESS...THIS WILL BE THE
4TH DAY OF HEAT AND HUMIDITY IN OUR REGION WHICH IS SIGNIFICANT. WE
DID COLLABORATE WITH OUR SURROUNDING OFFICES TO REPLACE THE EXTREME
HEAT WARNING WITH AN ADVISORY...BUT THE OVERALL MESSAGE HAS NOT
CHANGED.
THE OTHER CONCERN FOR TODAY WILL BE ASSESSING THE CONVECTIVE
POTENTIAL. WE STILL EXPECT TO GENERATE SOME MODEST INSTABILITY
TODAY...BUT THE HIGHER INSTABILITY/STEEPER MID LEVEL LAPSE RATES
WILL BE TO OUR SOUTHWEST. WE OFTEN SEE THE CONVECTION TEND TO
GRAVITATE TOWARDS THE AXIS OF BETTER INSTABILITY. THE CAMS SEEMS TO
WANT TO FOLLOW THAT PATH AS WELL AS THEY SHOW THE MAIN POTENTIAL FOR
SEVERE WEATHER/DAMAGING WIND GUSTS AND MOST WIDESPREAD CONVECTION TO
OUR SOUTHWEST. THAT BEING SAID...GIVEN MODEST INSTABILITY AND
EFFECTIVE SHEAR OF 30-40 KNOTS WE CAN NOT RULE OUT A LOW PROBABILITY
OF SEVERE WEATHER IN OUR REGION. THIS IS PARTICULARLY TRUE ACROSS
SOUTHWEST MA/NORTHERN CT AS IT IS POSSIBLE THEY END UP ON THE
NORTHERN EDGE OF COMPLEX OF THUNDERSTORMS.
SO IN A NUTSHELL...A FEW SHOWERS & T-STORMS ARE POSSIBLE THIS
AFTERNOON INTO TONIGHT BUT NOT EXPECTING A WASHOUT. WHILE A LOW RISK
FOR SEVERE WEATHER CAN NOT BE RULED OUT...APPEARS THE GREATER
POTENTIAL WILL BE TO OUR SOUTHWEST. IF ANY SEVERE WEATHER WERE TO
OUR OCCUR IN OUR REGION THE MAIN RISK WOULD BE LOCALLY STRONG TO
DAMAGING STRAIGHT LINE WIND GUSTS AND BRIEF TORRENTIAL RAINFALL.
KEY MESSAGE 2...MUCH COOLER TEMPERATURES FOR THE FIRST HALF OF NEXT
WEEK AND THAT IS ESPECIALLY TRUE IF THE POTENTIAL FOR A SOAKING
HEAVY RAINFALL OCCURS IN THE LATE SUN INTO TUE TIME FRAME.
ALL OF THE MODEL GUIDANCE IS IN VERY GOOD AGREEMENT IN THE UPPER
LEVEL RIDGE BREAKING DOWN BRINGING MUCH COOLER TEMPERATURES FOR THE
FIRST HALF OF NEXT WEEK. NOW JUST HOW MUCH WE COOL WILL DEPEND UPON
IF A POTENTIAL SOAKING HEAVY RAIN OCCURS IN THE LATE SUN THROUGH TUE
TIME FRAME. THIS PART OF THE FORECAST REMAINS QUITE UNCERTAIN. THERE
ARE INGREDIENTS IN PLACE THAT WOULD SUPPORT A HEAVY RAINFALL WITH
HIGH PRESSURE OVER EASTERN CANADA AND LOW PRESSURE PASSING TO OUR
SOUTH. THIS SETS UP A POTENTIAL OVER RUNNING SETUP FOR BAND OF HEAVY
RAIN AND PERHAPS EMBEDDED THUNDERSTORMS. THE ENSEMBLES SHOW A LARGE
SPREAD IN POTENTIAL OUTCOMES FROM VERY LIMITED RAINFALL TO SEVERAL
INCHES OF RAIN! TRYING TO FORECAST SYNOPTIC RAINFALL DURING THE
SUMMER WHEN BAROCLINICITY IS WEAK AND CONVECTIVE PROCESSES ARE
INVOLVED IS QUITE DIFFICULT. WE WILL NEED MORE TIME TO SORT THIS
OUT. HOWEVER...GIVEN SUMMER PWATS OF 1.5-2+ INCHES IF WE ARE ABLE TO
GET SUFFICIENT FORCING IN OUR REGION THEN THE POTENTIAL HEAVY
RAINFALL WOULD BE REALIZED. THAT REMAINS TO BE SEEN BUT SOMETHING WE
WILL CONTINUE TO WATCH.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
06Z TAF UPDATE...
TODAY THROUGH SUNDAY...HIGH CONFIDENCE.
VFR CONDITIONS DOMINATE TODAY THROUGH SUNDAY. WE WILL NEED TO WATCH
FOR A FEW SHOWERS AND ISOLATED T-STORMS MAINLY THIS AFTERNOON AND
TONIGHT. AREAL COVERAGE LOOKS LIMITED WITH THE GREATEST RISK ACROSS
SOUTHWEST MA/CT WHERE THEY MAY BE ON THE NORTHERN EDGE OF A COMPLEX
OF CONVECTION LATE TODAY INTO THIS EVENING.
WNW WINDS MAY BUT TO 20+ KNOTS AT TIMES THIS AFTERNOON. WINDS
DIMINISH TONIGHT AND TURN LIGHT N/CALM BEFORE COMING LIGHT E ON SUN.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...
SUNDAY NIGHT: VFR. CHANCE SHRA.
MONDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY. NUMEROUS
SHRA, ISOLATED TSRA.
MONDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.
NUMEROUS SHRA, SLIGHT CHANCE TSRA.
TUESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.
SCATTERED SHRA, ISOLATED TSRA.
TUESDAY NIGHT THROUGH WEDNESDAY: VFR. SLIGHT CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH SUNDAY...HIGH CONFIDENCE.
A RELATIVELY WEAK PRESSURE GRADIENT WILL KEEP WINDS/SEAS BELOW SMALL
CRAFT ADVISORY THRESHOLDS THIS HOLIDAY WEEKEND. SOME 20+ KNOT WNW
WIND GUSTS OVER THE LAND LATER THIS MORNING AND AFTERNOON MAY RESULT
IN SOME NEAR SHORE CHOP...BUT NO HEADLINES WILL BE NEEDED FOR THE
WATERS THIS WEEKEND WITH SEAS GENERALLY 3 FEET OR LESS.
OUTLOOK /SUNDAY NIGHT THROUGH WEDNESDAY/...
SUNDAY NIGHT: WINDS LESS THAN 25 KT. CHANCE OF RAIN SHOWERS.
MONDAY: WINDS LESS THAN 25 KT. SCATTERED RAIN SHOWERS, ISOLATED
THUNDERSTORMS.
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. NUMEROUS RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.
TUESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SCATTERED RAIN
SHOWERS, ISOLATED THUNDERSTORMS.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. CHANCE
OF RAIN SHOWERS.
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT
CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR CTZ002>004.
MA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MAZ002>023-026.
RI...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR RIZ001>007.
MARINE...NONE.
DISCUSSION...FRANK
AVIATION...FRANK
MARINE...FRANK
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