959
FXUS61 KBOX 211926
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
326 PM EDT SUN JUN 21 2026
WHAT HAS CHANGED
NO CHANGES TO THE FORECAST AT THIS TIME.
KEY MESSAGES
- WHILE THE RISK FOR SEVERE WEATHER REMAINS LOW, DIURNAL THUNDERSTORMS
ARE A POSSIBILITY THROUGH THE END OF THE WEEKEND. OTHERWISE,
COOLER WITH WESTERLY BREEZES.
- PERIODS OF HEAVY RAIN POSSIBLE MONDAY INTO EARLY TUESDAY.
- DRIER AIR WITH SEASONABLE TEMPERATURES EXPECTED MIDWEEK.
CHANCES FOR RAIN RETURN FOR THE END OF NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...SCATTERED DIURNAL THUNDERSTORMS LINGER THROUGH
THIS EVENING.
ALREADY SEEING SOME THUNDERSTORMS FIRE ACROSS NH, VT, AND
UPSTATE NY. THESE WILL LIKELY PUSH SOUTH INTO SOUTHERN NEW
ENGLAND, ESPECIALLY ACROSS THE NORTH COAST AND EASTERN MA. CAPE
VALUES 350- 550 J/KG THROUGH SUNSET WILL PROVIDE ENOUGH
INSTABILITY FOR THUNDERSTORMS TO LINGER INTO THE EVENING HOURS;
HOWEVER, NOT EXPECTING STORMS TO BECOME SEVERE IN NATURE.
KEY MESSAGE 2...PERIODS OF HEAVY, BENEFICIAL RAIN POSSIBLE
MONDAY INTO TUESDAY.
A MUCH NEEDED WIDESPREAD, SOAKING RAIN IS EXPECTED WITH THE
PASSAGE OF A LOW PRESSURE SYSTEM MONDAY INTO TUESDAY. THE
PROBABILITY FOR 1+ INCH OF STORM TOTAL RAINFALL REMAINS BETWEEN
70 TO 80 PERCENT ACROSS MOST OF SOUTHERN NEW ENGLAND, WITH 80+
PERCENT PROBS ACROSS THE INTERIOR. THE PROBABILITY FOR 2+ INCHES
OF RAINFALL REMAINS ABOUT 30 TO 50 PERCENT. LATEST FLASH FLOOD
GUIDANCE FROM NERFC IS SHOWING WE NEED AT LEAST 2.5" IN 1 HOUR
(3.5"+ IN 3 HOURS), SO WHILE THESE RAINS WILL BE BENEFICIAL,
FLOODING IS NOT EXPECTED ACROSS THE REGION. WE SHOULD DRY OUT
FROM WEST TO EAST AS A LOW PRESSURE ALONG THE SOUTH COAST OF NEW
ENGLAND MOVES OFFSHORE TUESDAY.
KEY MESSAGE 3...DRIER AIR WITH SEASONABLE TEMPERATURES EXPECTED
MIDWEEK. CHANCES FOR RAIN RETURN FOR THE END OF NEXT WEEK.
SURFACE HIGH PRESSURE WILL KEEP THE WEATHER DRY THROUGH THE
MIDDLE OF THE WEEK, AFTER THE RAIN COMES TO AN END ON TUESDAY.
HIGH TEMPERATURES WILL BE IN THE LOW TO MID 80S, POSSIBLY
CREEPING TOWARDS THE UPPER 80S ACROSS CT, RI, AND PARTS OF
SOUTHERN AND EASTERN MA BY THE WEEKEND. A LOW PRESSURE SYSTEM
WILL MOVE INTO THE GREAT LAKES REGION BY THURSDAY, THEN TRACKING
INTO SOUTHEASTERN CANADA BY THE END OF THE WEEK, WITH A WEAK
SHORTWAVE TROUGH TRACKING ACROSS THE NORTHEAST. THIS SYSTEM WILL
BRING THE NEXT CHANCES FOR RAIN TO NEW ENGLAND, AND TO MUCH OF
THE MID ATLANTIC AS WELL, BEGINNING BY FRIDAY MORNING. ISOLATED
TO SCATTERED THUNDERSTORMS ARE POSSIBLE FRIDAY AFTERNOON, WITH
THE HIGHEST CHANCES OVER WESTERN MA. THE GEFS HAS LOW, BUT NON-
ZERO, PROBABILITY FOR SEVERE STORMS FRIDAY, AS WELL AS SOME OF
THE OTHER ENSEMBLE AND MACHINE LEARNING GUIDANCE, BUT HOW HIGH
THAT PROBABILITY IS VARIES FAIRLY SIGNIFICANTLY AMONG GUIDANCE.
GIVEN THIS SPREAD, AND HOW FAR OUT IN THE FORECAST IT IS,
CONFIDENCE ON OVERALL SEVERE POTENTIAL IS LOW. HIGH TEMPERATURES
COULD BE TEMPERED A BIT UNDER CLOUD COVER AND RAIN FOR FRIDAY,
BUT REBOUND OVER THE WEEKEND AS THE FRONT MOVES AWAY FROM THE
REGION.
AVIATION /19Z SUNDAY THROUGH FRIDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH TONIGHT: HIGH CONFIDENCE.
VFR. W/WNW 9-12 KTS WITH A FEW GUSTS UP TO 20 KTS POSSIBLE
THROUGH THE AFTERNOON. A FEW POPUP SHOWERS LIKELY MOVE THROUGH,
PRIMARILY ACROSS EASTERN MA, POSSIBLY INTO RI.
ONCE SHOWERS MOVE OFFSHORE THIS EVENING, WINDS RETURN TO
PRIMARILY WESTERLY AND BECOME LIGHT IN NATURE.
MONDAY: HIGH CONFIDENCE.
VFR FOR MOST OF THE DAY. S/SSE 8-12 KTS. MVFR CEILINGS ARRIVE
FROM WEST TO EAST IN THE AFTERNOON WITH THE ARRIVAL OF RAIN.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. FEW POPUP SHOWERS
WITH A RUMBLE OF THUNDER OR TWO POSSIBLE GENERALLY BETWEEN
20-24Z.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY. CHANCE
SHRA, SLIGHT CHANCE TSRA.
TUESDAY NIGHT THROUGH THURSDAY: VFR.
THURSDAY NIGHT: VFR. CHANCE SHRA, SLIGHT CHANCE TSRA.
FRIDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. CHANCE SHRA,
CHANCE TSRA.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH MONDAY NIGHT...HIGH CONFIDENCE.
THE RISK FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
CONTINUES FOR THIS AFTERNOON AND EVENING, ESPECIALLY ALONG THE
EASTERN COAST OF MA. THIS ACTIVITY SHOULD WANE AFTER SUNSET.
A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE SOUTHERN WATERS
SOUTH OF BLOCK ISLAND AND EAST TO NANTUCKET FOR MONDAY AFTERNOON
INTO TUESDAY MORNING. GUSTS UP TO 25 KNOTS ARE POSSIBLE, ALONG
WITH WAVE HEIGHTS BETWEEN 4 TO 6 FT. RAIN SHOWERS WITH A CHANCE
FOR STORMS MONDAY THROUGH TUESDAY.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. RAIN SHOWERS,
CHANCE OF THUNDERSTORMS. LOCAL VISIBILITY 1 TO 3 NM.
TUESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: WINDS LESS THAN 25 KT.
FRIDAY: WINDS LESS THAN 25 KT. CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM MONDAY TO 8 AM EDT TUESDAY FOR
ANZ255-256.
DISCUSSION...MCMINN/SAVA
AVIATION...MCMINN
MARINE...MCMINN/SAVA
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