FXUS61 KBOX 081611
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1111 AM EST TUE DEC 8 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO NEW ENGLAND TODAY. A STRONG STORM WILL
AFFECT SOUTHERN NEW ENGLAND WEDNESDAY WITH A MIX OF PRECIPITATION AND
WIND. COLDER AND BLUSTERY WEATHER WILL FOLLOW FOR THE END OF THE WEEK
INTO THE WEEKEND. THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE
PATH OF LOW PRES DEVELOPING OFF THE EAST COAST NEXT SUNDAY.
&&
.NEAR TERM /UNTIL 9 PM THIS EVENING/...
1110AM: NO HAZARD CHANGES AT MIDDAY. WE DID RCV ONE MEDIA REQUEST FOR
CONSIDERING AN UPGRADE OR ISSUANCE OF A WXA. WE THINK THERE IS ENOUGH
TIME TO ISSUE ADVISORIES OR WARNINGS AT 4PM. WE RUN COMPLEX TOOLS TO
GENERATE OUR GRIDS WHICH TAKE CONSIDERABLE TIME TO EMPLOY. FROM THOSE...
WE IN TURN GENERATE OUR AUTOMATED WORDED FORECASTS. WE WOULD LIKE TO
BALANCE OUR APPROACH USING ALL THE STANDARD MODEL GUIDANCE INCLUDING
NON NCEP GUIDANCE.
IN THIS CASE...I AM CONCERNED ABOUT CONTD NAM COLDNESS AND PREFER A
WARM SOLN WITH A STRONG PRIMARY LOW TO OUR WEST. IN ALL LIKELIHOOD WE
WILL RUN 50 50 BLENDS OF THE 12Z NAM/GFS PARTIAL THICKNESSES AND USE
THE UPCOMING 18Z HPC QPF.
NO MATTER...THE 11 AM HAZARD PRODUCTS ARE POSTED. EMPHASIZE A
DIFFICULT 3-6 HOUR PERIOD BETWEEN ROUGHLY 430AM AND 1030AM AND
WINTER WX IMPROVEMENT THEREAFTER.
WIND WATCH PROBLEMS NOW ADVERTISED FOR CC MIGHT ALSO OCCUR VCNTY BOS
AND GLOUCESTER.
847 AM: I KNOW I BUSTED LAST NIGHTS SHOWER FCST FOR CC WITH ONLY
TRACES AS IT APPEARS MEASURABLE SHOWERS DEVELOPED 30 MI TO THE E OF
THE MODELED GUIDANCE THAT I WAS RELYING UPON /GFS/SREF/NAM/RGEM.
YDYS MIN TEMP FCST VERIFIED FAIRLY WELL I95 CORRIDOR EAST BUT 3-5
WARMER THAN EXPECTED IN CT THIS MORNING AND 3-5 COLDER IN S NH AND NW
MA RADIATORS.
TEMPS HAVE BEEN ADJUSTED DOWNWARD THRU MID MORNING AND WE AGAIN MAY
BE UNDERCUTTING TEMPS DURING MIDDAY IN OUR 10 AM UPDATE.
WINDS WERE INCREASED THIS MORNING COASTAL MASS.
A NICE DAY AS HIGH PRES IN PA BUILDS NEWD INTO NEW ENGLAND.
NO UPDATES EXPECTED FOR THE WSW/NPW ETC IN THE 10 AM PACKAGE.
STILL MONITORING FOR CFA BOS TO NBT AND FOX PT RI WED AFTN. CURRENT
FCST SNOW MAP ON OUR HPAGE IS VERY CLOSE TO 03Z SREF WINTER WX IMPACT
GRAPHICS AND THE 05Z INTERNAL WWD COLLAB.
&&
.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
*** VARIETY OF IMPACTS FORESEEN WED ***
STRENGTHENING LOW PRESSURE HEADING TO GREAT LAKES WILL BRING SEVERAL
CONCERNS TO SOUTHERN NEW ENGLAND INCLUDING BRIEFLY HEAVY SNOW TO
MUCH OF REGION FOR MORNING COMMUTE...STRONG AND POSSIBLY DAMAGING
WINDS TO CAPE COD AND ISLANDS AND GALE FORCE WINDS TO COASTAL
WATERS. MINOR COASTAL FLOODING IS ALSO A CONCERN WITH WED HIGH
TIDE.
WINTRY WX...
ALTHOUGH THERE ARE DIFFERENCES AMONG MODELS WITH REGARD TO TIMING
AND AMOUNT OF WARMING WHICH DICTATES PRECIPITATION TYPE...ALL ARE
SHOWING POTENTIAL FOR AT LEAST A PERIOD OF HEAVY SNOW ACROSS INTERIOR
WED MORNING BEFORE A TRANSITION TO SLEET/FREEZING RAIN AND FINALLY RAIN
IN THE AFTERNOON. THIS DOES NOT HAVE MAKINGS OF A SIGNIFICANT ICE
STORM BUT THERE SHOULD BE SOME ICING DURING TRANSITION.
TEMPERED FASTER GFS TIMING WITH SLOWER NAM...SINCE GFS LOOKS TOO FAST
WITH DRY LOW LEVEL AIR IN PLACE AND NAM APPEARS TO BE TOO SLOW. THIS
BRINGS SNOW INTO CT VALLEY 3-5 AM AND TO E COAST 5-7 AM. STAYED CLOSE
TO HPC QPF.
THERE ARE STILL A FEW RED FLAGS WHICH LEAD TO LOWER CONFIDENCE THAN
USUAL. AIR MASS IN PLACE WILL NOT BE UNUSUALLY COLD... AND WITH
INCREASING ONSHORE FLOW IT WON/T TAKE MUCH TO WARM THINGS UP. IN
ADDITION...MAIN SURFACE LOW TRACKS TO OUR W WITH ONLY A HINT OF
SECONDARY REDEVELOPMENT TO MAINTAIN COLD AIR. WAVE ALOFT REMAINS OPEN
WHICH MEANS A MORE PROGRESSIVE SYSTEM...AND SW FLOW SHOULD ALLOW FOR
RAPID WARMING ALOFT...POTENTIALLY CUTTING DOWN ON SNOWFALL AMOUNTS.
00Z NAM REMAINS COLDEST OF MODELS...ALTHOUGH GFS/RGEM/ECMWF NOT FAR
BEHIND. NAM/GFS CROSS SECTIONS SHOW GOOD MESOSCALE BANDING SIGNATURE
AS WELL AS DECENT SNOW GROWTH ACROSS INTERIOR. EVEN CLOSER TO
COAST... STRONG DYNAMICS CAN COMPENSATE FOR LOW LEVEL WARMING. NOTED
21Z SREF PROBS WHICH HAVE INCREASED FOR 8 INCHES ACROSS MUCH OF
INTERIOR. SREFS ALSO SHOW POTENTIAL FOR 1-2"/HR SNOWFALL RATES AND
LOW VISIBILITY DURING WED MORNING COMMUTE.
GIVEN TRENDS IN SREF/OPERATIONAL MODELS WE HAVE TRENDED FORECAST A
BIT COLDER AND WITH SOMEWHAT HIGHER ACCUMULATIONS. THESE TYPES OF
SYSTEMS CAN BE NOTORIOUS FOR PRODUCING SIGNIFICANT SNOWS AT THE
START...YET AT SAME TIME AMOUNTS CAN BE OVER FORECAST DUE TO RAPID MID
LEVEL WARMING. HOWEVER WE DO HAVE ENOUGH CONFIDENCE TO ISSUE WINTER
STORM WATCHES FOR SW NH AND NW/CENTRAL/INTERIOR NE MA. WE ALSO
CONSIDERED WATCH A LITTLE FARTHER S /HARTFORD SPRINGFIELD/ DUE TO
IMPACT ON THE MORNING COMMUTE...BUT DECIDED TO HOLD OFF GIVEN LOWER
CONFIDENCE.
WE ARE FAIRLY CONFIDENT IN A WIDESPREAD ADVISORY-LEVEL EVENT ADJACENT
TO WATCH AREA /NORTHERN CT NORTHERN RI AND MUCH OF EASTERN MA/.
STRONG WINDS...
INCREASING SE LOW LEVEL JET OF 70+KT WILL HAVE A HARD TIME MIXING TO
SURFACE GIVEN WARM AIR ALOFT...BUT TIGHTENING GRADIENT SHOULD SUPPORT
AT LEAST ADVISORY LEVEL /40KT/ GUSTS ALONG IMMEDIATE COAST. WE WILL
ISSUE A HIGH WIND WATCH FOR CAPE COD AND ISLANDS DUE TO POTENTIAL FOR
45-50KT GUSTS AND/OR WIND DAMAGE. GMOS INDICATES 50+KT GUSTS WED
AFTERNOON WHICH MAY BE OVERDONE...OUTPUT FROM MIXING HEIGHT SHOWS
40-45KT GUSTS MORE LIKELY. HOWEVER GIVEN SOME UNCERTAINTY WE OPTED
FOR WATCH AT THIS TIME.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE MID TO LONG RANGE MODELS AND THE GFS/GLOBAL ENSEMBLES ARE FAIRLY
GOOD AGREEMENT REGARDING THE MEAN SYNOPTIC SCALE FLOW THROUGH
FRIDAY..THEN BEGIN TO DIVERGE DAYS 5 THROUGH 7. THE TELECONNECTIONS
FAVOR A NEGATIVE NAO PATTERN WITH THE PNA BECOMING POSITIVE. THIS
GENERALLY FAVORS COLDER THAN NORMAL TEMPERATURES ACROSS THE AREA
DURING THE EXTENDED TIMEFRAME.
WEDNESDAY NIGHT...LEFTOVER SNOW AND RAIN SHOWERS WITH CYCLONIC FLOW
PREVAILING BEHIND A DEPARTING CANADIAN MARITIMES LOW. TURNING WINDY
AND COLDER.
THURSDAY THROUGH FRIDAY...BLUSTERY CONDITIONS...A COLD NORTHWEST
FLOW PREVAILS AS DAILY AVERAGE TEMPERATURES TURN MORE REFLECTIVE OF
JANUARY...ESPECIALLY FRIDAY AS 1000-500MB THICKNESSES DROP DOWN INTO
THE 510S! USED A 50/50 BLEND OF RAW 2M AND MOSGUIDE TEMPERATURES
DURING THIS PERIOD. DIURNAL CLOUDS AND SCATTERED FLURRIES WILL BE
POSSIBLE DUE TO CYCLONIC FLOW AT H85 AND ALOFT. THIS COULD BRING SOME
LAKE MOISTURE INTO THE REGION. MENTIONED SLIGHT CHANCE POPS AT THIS
TIME. WIND CHILLS ARE EXPECTED TO DROP INTO THE SINGLE NUMBERS AND
TEENS THURSDAY NIGHT THROUGH FRIDAY NIGHT.
SATURDAY THROUGH MONDAY...POTENTIAL FOR BRIEF RIDGING AND MODERATION
ON SATURDAY BEFORE THE NEXT COLD FRONT APPROACHES. THERE IS SOME
UNCERTAINTY WHETHER SUBTROPICAL MOISTURE WILL BE ABLE TO REACH THIS
FAR NORTH BY SUNDAY. LONG RANGE MODELS ARE IN SPLIT CAMPS AS THE 00Z
ECMWF/UKMET HAVE A COASTAL LOW ADVERTISED TO TRACK JUST SOUTHEAST OF
THE BENCHMARK WHILE THE 00Z OPERATIONAL GFS/GLOBAL GEM SUPPRESS THIS
MOISTURE FURTHER SOUTH OF THE AREA. FOR NOW HAVE INCLUDED A LOW CHANCE
POP ACROSS SOUTHEASTERN AREAS WITH SLIGHT CHANCE POPS INLAND. THIS
WILL DEPEND WHEN PHASING IS EXPECTED TO OCCUR...AND DO NOT HAVE HIGH
CONFIDENCE IN THE RESULTS THIS FAR OUT IN TIME.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
TODAY...VFR FOR ALL TAF SITES. 3000 FT CIGS OUTER CAPE COD THROUGH
EARLY AFTN....CQX TO PVC. NW WIND 10-20 KT CAPE COD AND THE ISLANDS
THIS MORNING.
MID AND HIGH CLOUDS BEGIN TO INCREASE W PTN THIS AFTN BUT CIGS AOA
15KFT EXPECTED THROUGH 06Z WED.
CIGS LOWER STEADILY 08Z-12Z WED AS SNOW OVERSPREADS SOUTHERN NEW
ENGLAND. KBDL/KBAF/KORH LIKELY TO BECOME IFR/LIFR TOWARD 12Z...
WHILE MVFR CONDITIONS EXPECTED ELSEWHERE.
MVFR/IFR LIKELY WED WITH LIFR ACROSS HIGHER TERRAIN. BEST ESTIMATES
ON TIMING FOR SOME SITES...
KBOS/KPVD...SNOW CHANGES TO RAIN BY 14Z. 1-2 INCH ACCUM.
KBDL...SNOW CHANGES TO FZRA/PL BY 14Z THEN TO RAIN BY 16Z. 3-5 INCH
ACCUM. POTENTIAL FOR 1/2SM VSBY 10Z-13Z.
KMHT...SNOW CHANGES TO FZRA/PL BY 17Z THEN TO RAIN BY 20Z. 4-6 INCH
ACCUM. POTENTIAL FOR 1/2SM VSBY 13Z-16Z.
IN ADDITION...E WINDS LIKELY TO GUST TO 40KT KBOS-KACK.
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...
WEDNESDAY NIGHT THROUGH FRIDAY...VFR CONDITIONS. NW WINDS GUSTING UP
TO 35 TO 40 KT AT TIMES THROUGH FRIDAY. WINDS DIMINISHING A BIT
FRIDAY NIGHT AWAY FROM THE COAST AND BY LATE SATURDAY ALL AREAS.
MECHANICAL WIND SHEAR/TURBULENCE EXPECTED.
&&
.MARINE...
GALE WARNINGS ALL WATERS WED...THOUGH IT IS POSSIBLE GUSTS REACH
STORM FORCE.
OTRW...SCA CONDS THIS MORNING PORTIONS OF THE WATERS SUPERSEDED BY
THE GALE WARNING. DIMINISHING WINDS AND SEAS MIDDAY AS HIGH PRESSURE
BUILDS ACROSS WATERS.
E/NE WINDS INCREASE LATE TONIGHT AND SHOULD REACH GALE FORCE AROUND
OR JUST AFTER DAYBREAK WED. STRONGEST WINDS EXPECTED FROM LATE
MORNING INTO AFTERNOON...BEFORE SHIFTING TO SW /S COAST/ AND
DIMINISHING SOMEWHAT.
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...
WEDNESDAY NIGHT THROUGH FRIDAY...HIGH PROBABILITY OF GALES THROUGH
FRIDAY NIGHT AS EXCELLENT WIND MOMENTUM TRANSFER IS EXPECTED DUE TO
STRONG COLD AIR ADVECTION OVER THE RELATIVELY WARM ATLANTIC WATERS.
COULD SEE GUSTS TO 35 TO 45 KT THROUGH FRIDAY NIGHT...POSSIBLY
DIMINISHING TO SMALL CRAFT LATE SATURDAY.
&&
.HYDROLOGY...
PRECIPITATION TOTALS /MOSTLY RAIN/ OF 1 TO 1.5 INCHES ARE POSSIBLE
NEAR COAST BY WED EVENING. WHILE THIS MAY RESULT IN URBAN AND POOR
DRAINAGE FLOODING...ESPECIALLY NEAR S COAST...MAINSTEM RIVERS ARE
EXPECTED TO REMAIN WITHIN THEIR BANKS.
&&
.TIDES/COASTAL FLOODING...
MINOR COASTAL FLOODING IS POSSIBLE AROUND TIME OF HIGH TIDE WED
AFTERNOON...MAINLY ON E FACING COASTLINE BOS-NBT NORTHWARD AND
POSSIBLY UPPER NARR BAY. TIMING OF HIGH TIDE FOR CC AND ACK SEEMS
NOT TO MESH THAT WELL WITH HIGHEST SURGE BUT ITS NOT IMPOSSIBLE.
AM CONCERNED ABOUT PLUM ISLAND TO MARBLEHEAD WED AFTN HIGH TIDE.
REREVIEWING AT 1PM.
ASTRONOMICAL TIDES ARE NOT UNUSUALLY HIGH...BUT COMBINATION OF STRONG
ONSHORE WINDS AND LARGE PRESSURE FALLS LIKELY RESULTS IN STORM SURGE
OF 1 TO 2 FT E MA COAST AND 2 TO POSSIBLY 3 FT UPPER NARR BAY FOR WED
AFTN HIGH TIDE CYCLE.
AS HAS BEEN CONSISTENT THIS FALL...MRPSSE GUIDANCE CONTS TO UNDERPLAY
THE POSITIVE SURGE AND CLEARLY HAS A LOW BIAS. AT 13Z ITS UNDER PREDICTING
REALITY BTWN .25 TO .6 FT.
&&
.EQUIPMENT...
GLOUCESTER NWR TRANSMITTER IS NOW ON THE AIR. JOHNSTON/PROVIDENCE NWR
TRANSMITTER IS ALSO BACK ON THE AIR BUT ON LOW POWER...SOME SOUTH
COASTAL LOCATIONS MAY BE UNABLE TO RECEIVE THE SIGNAL. MORE
MAINTENANCE WILL BE DONE TO RETURN THIS STATION TO FULL POWER. IN THE
MEANTIME...PLEASE SEE OUR WEBSITE... WWW.WEATHER.GOV/BOSTON FOR
WEATHER INFORMATION.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY
AFTERNOON FOR MAZ002>006-008-010-012-026.
HIGH WIND WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
AFTERNOON FOR MAZ022>024.
NH...WINTER STORM WATCH FROM LATE TONIGHT THROUGH WEDNESDAY
AFTERNOON FOR NHZ011-012-015.
RI...NONE.
MARINE...GALE WARNING FROM 7 AM TO 5 PM EST WEDNESDAY FOR ANZ230>237-
250-251-254>256-270>273.
&&
$$
SYNOPSIS...DRAG/STRAUSS/JWD
NEAR TERM...DRAG/STRAUSS/JWD 1110A
SHORT TERM...DRAG/JWD
LONG TERM...STRAUSS
AVIATION...DRAG/STRAUSS/JWD 1110A
MARINE...DRAG/STRAUSS/JWD
HYDROLOGY...
TIDES/COASTAL FLOODING...
EQUIPMENT...
