166
FXUS61 KBOX 040148
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
948 PM EDT FRI JUL 3 2009
SYNOPSIS
LOW PRESSURE OVER THE NORTHEAST MOVES TO QUEBEC SAT FORCING A COLD
FRONT ACROSS OUR AREA. DRIER WEATHER ARRIVES SUNDAY INTO MONDAY.
THE MIDDLE OF NEXT WEEK MAY BECOME UNSETTLED AS VERY WARM AIR TRIES
TO INVADE THE NORTHEAST USA FOR A DAY OR 2.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
CONVECTION CONTINUES TO DIMINISH ACROSS THE AREA. REDUCED OVERNIGHT
POPS FROM LOW TO SLIGHT CHANCE.
MADE SOME MINOR MODIFICATIONS TO HOURLY TEMPERATURES AND DEWPOINTS
SHORTLY.
PATCHY FOG CAN BE EXPECTED ACROSS THE INTERIOR VALLEYS AND THE CAPE
AND ISLANDS TONIGHT BUT LESS WIDESPREAD AND NOT AS DENSE AS PREVIOUS
NIGHTS.
SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/
SATURDAY...
A STRONG SHORTWAVE WILL DROP DOWN IN NORTHWEST FLOW ALOFT. THIS
WILL BRING AN AREA OF VERY COLD AIR ALOFT INTO THE NORTHERN AND
EASTERN SECTIONS OF OUR REGION...WITH 500 MB TEMPERATURES DROPPING
TO BETWEEN -15C AND -17C. MID LEVEL LAPSE RATES ARE EXPECTED TO
INCREASE TO BETWEEN 6.5 AND 7 C/KM ACROSS SOUTHERN NH/NORTHEAST MA.
AT THE SAME TIME THOUGH...DRIER AIR WILL BE WORKING IN FROM THE
NORTHWEST.
THERE LOOKS TO BE A SMALL WINDOW FROM MID TO LATE MORNING INTO THE
EARLY AFTERNOON...WHERE MARGINAL INSTABILITY MAY COMBINE WITH
INCREASING WIND FIELDS AND COLD AIR ALOFT. THIS MAY BRING A FEW STRONG
THUNDERSTORMS INTO OUR NORTHERN AND EASTERN SECTIONS OF THE CWA.
BOTH THE GFS AND SREF ENSEMBLES INDICATE THE POTENTIAL FOR AROUND 500
J/KG OF CAPE ACROSS SOUTHERN NH/NORTHEAST MA. THEREFORE...WILL
INCLUDE A FEW HOURS OF CHANCE POPS IN THIS REGION AND QUICKLY TAPER
POPS DOWN SOUTHWESTWARD. EITHER WAY THE MOST OF THE DAY SHOULD BE
DRY...OTHER THAN THE RISK FOR A BRIEF SHOWER OR THUNDERSTORM.
UNCERTAINTY REVOLVES AROUND THIS FORECAST SINCE THERE IS A
RELATIVELY SMALL WINDOW...BEFORE THE DRY AIR COMES RUSHING INTO THE
REGION. HOWEVER...THE POTENTIAL EXISTS FOR A FEW STRONG
THUNDERSTORMS ACROSS SOUTHERN NH/NORTHEAST MA FROM MID MORNING INTO
THE EARLY AFTERNOON. WHAT EVER HAPPENS...ANY RISK FOR CONVECTION
SHOULD COME TO AN END BY LATE AFTERNOON.
HIGH TEMPERATURES SHOULD REACH INTO THE LOWER 80S WITH PARTLY SUNNY
SKIES AND A WESTERLY FLOW OF AIR. IN FACT...WE EXPECT WIND GUSTS TO
AROUND 25 MPH IN THE LATE MORNING AND AFTERNOON.
SATURDAY NIGHT...
A DRY NIGHT IS EXPECTED ACROSS SOUTHERN NEW ENGLAND BUT IS MAY BE A
BIT BREEZY INTO THE EARLY EVENING. THE DRY AIRMASS SHOULD ALLOW LOW
TEMPERATURES TO FALL MAINLY INTO THE 50S...WITH LOWER 60S IN THE
URBAN HEAT ISLANDS OF BOSTON.
LONG TERM /SUNDAY THROUGH FRIDAY/
SUNDAY...DRY WITH MARITIMES LOW PRES THE PRIMARY INFLUENCE RESULTING
IN A GUSTY WEST WIND. A VERY NICE SUNDAY. ANOTHER AREA OF LOW PRES
SHOULD REMAIN FAR ENOUGH SOUTH TO BARELY THREATEN THE S COAST AT
NIGHT. TEMPS ARE 12Z GFS MOS BLENDED WITH THE 4AM KBOX FCST. WIND
GUSTS ARE 12Z NAM MXG HTS AND GUST ALG.
MONDAY-TUESDAY...CONTINUITY WITH SORT OF AN IN BETWEEN TRANSITION. CUD
BE A LATE MONDAY AFTN TSTM IN THE INTERIOR. LOTS OF UNCERTAINTY.
WED-THU...MODEL DISPARITY PREVAILS BUT IT SEEMS AS WED IS VULNERABLE
TO A SHOWER OR TSTM. THEN ON THURSDAY WE HAVE A PROBABLE DRY FCST AS
HIGH PRES MOVES OVERHEAD.
NEXT FRI...WAA FROM THE WEST. GEFS IS COOLER THAN THE EC AND EVEN THE
12Z GFS OP RUN SO HAVE 50 50 BLENDED THE 12Z GFS MOSGUIDE WITH THE
4AM KBOX FCST. IF ANYTHING...WE THINK NEXT FRI COULD BE WARMER THAN
NORMAL BUT CONFIDENCE ON THIS SOLN IS LESS THAN NORMAL.
FCST WINDS THIS SUNDAY/MONDAY ARE 50 50 BLEND GFS MOSGUIDE AND NAM THRU 84
HRS THEN 50/50 12Z GFS MOS AND 4AM EDT KBOX FCST FOR THE NEXT TUE-FRI
TIME FRAME.
FCST SKY...50 50 BLEND OF THE 12Z GFS MOS GUIDE AND THE 4AM EDT KBOX
FCST SUNDAY-FRIDAY THO I ADDED 20-30 PCT SKYCVR NEXT FRI...THIS DUE
TO THE WAA PATTERN AS THE HOT PROD IN THE NATIONS MID SECTION TRIES
TO INTRUDE UNDER WNW FLOW ALOFT-NE PERIPHERY OF THE MID USA RIDGE.
AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
SCATTERED SHOWERS/TSTMS ARE DEVELOPING UNDER COLD POOL ALOFT. MAIN
CONCENTRATION AT 18Z IS FROM BDL-PVD AND SREF PROBS FOR CAPE>500 J/KG
IS CAPTURING THIS AREA VERY WELL. SREF SUGGESTS GREATEST COVERAGE OF
CONVECTION THROUGH THIS AFTERNOON WILL BE NEAR OR JUST WEST OF I95
CORRIDOR. BRIEF MVFR/IFR CONDITIONS WITH BRIEF DOWNPOURS AND POSSIBLE
HAIL WILL ACCOMPANY ANY TSTMS...OTHERWISE VFR CIGS EXPECTED.
MEANWHILE...STRATUS DECK SOUTH OF THE CAPE IS ERODING SO MAINLY VFR
EXPECTED THIS AFTERNOON FMH-HYA-ACK.
TONIGHT...WDLY SCT MVFR SHOWERS AND THUNDERSTORMS POSSIBLE
EARLY...OTHERWISE VFR. IFR ST/FOG MAY DEVELOP AT ACK BY 00Z...AND
OVER INTERIOR TERMINALS AND HYA/FMH AFT 06Z.
SATURDAY...LOCAL IFR POSSIBLE EARLY...OTHERWISE VFR. SCT SHOWERS/TSTMS
ASSOCD WITH NEXT SHORTWAVE MAY BRING BRIEF MVFR CONDITIONS
14-18Z...PRIMARILY MHT-ORH-BOS. RAPID DRYING OCCURRING AFT 18Z WITH
WEST WIND GUSTS TO 25 KT POSSIBLE.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
GENERALLY VFR. WEST WIND GUSTS TO 25 KTS POSSIBLE SUNDAY 17Z-23Z.
MARINE
TONIGHT...A FEW THUNDERSTORMS WILL AFFECT THE WATERS THIS EVENING.
THE STRONGEST STORMS MAY CONTAIN BRIEF GUSTY WINDS AND HAIL.
OTHERWISE...SEAS OVER THE OUTER WATERS WILL GENERALLY BE BETWEEN 2
AND 4 FEET. HOWEVER...5 FOOT SEAS MAY FLIRT WITH THE OUTER-WATERS.
SATURDAY...ENOUGH WESTERLY FLOW EXPECTED TO BRING SEAS TO 5 FEET
ACROSS OUR SOUTHERN OUTER-WATERS...SO WILL HOIST A SCA IN THIS
REGION. IN ADDITION...WESTERLY FLOW AND GOOD MIXING SUPPORT 20 TO
25 KNOT WIND GUSTS ESPECIALLY NEAR SHORE. LATER SHIFTS WILL HAVE TO
CONSIDER A SCA FOR THE REST OF OUR REGION...BUT CONFIDENCE NOT HIGH
ENOUGH TO HOIST AT THIS TIME.
SATURDAY NIGHT...WINDS AND SEAS SHOULD DROP BELOW SCA THRESHOLDS.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
NO HEADLINES ATTM THO WLY WIND GUSTS TO 25 KNOTS SUN AFTN MAY PROMPT A
PARTIAL E MA COAST SHORT TERM SCA.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EDT SATURDAY FOR ANZ254-
255.
SYNOPSIS...WTB/DRAG/STRAUSS
NEAR TERM...STRAUSS
SHORT TERM...FRANK
LONG TERM...DRAG
AVIATION...KJC/DRAG
MARINE...DRAG/FRANK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page