000
FXUS61 KBOX 070755
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
255 AM EST WED JAN 7 2009
.SYNOPSIS...
A POTENTIALLY DANGEROUS ICE STORM IS IN PROGRESS FOR SOUTHERN NEW
ENGLAND AND WILL SHIFT TO MOSTLY WEST TWO THIRDS OF MASSACHUSETTS...
ELEVATIONS OF NORTH CENTRAL CONNECTICUT AND ALL OF SOUTHERN NH DURING
THE DAYLIGHT HOURS TODAY. MAINLY DRY AND COLDER WEATHER RETURNS FOR
THE END OF THIS WEEK. MORE SNOW IS POSSIBLE SAT AND SAT NIGHT AS A
FAST MOVING CLIPPER TRACKS ALONG OR SOUTH OF THE COAST. COLDER AND
DRIER CONDITIONS SHOULD FOLLOW FOR SUNDAY AND MONDAY.
&&
.NEAR TERM /UNTIL 10 AM THIS MORNING/...
ICE STORM IN PROGRESS AND THIS IS LOOKING DANGEROUS WITH POWER OUTAGE
RISK INCREASING FOR THE W TWO THIRDS OF MASS...ESP HIGHER TERRAIN AS
WELL W HFD COUNTY HIGH TERRAIN INTO S CENTRAL NH.
SKYWARN ACTIVATION 530AM. SKYWARN PRESENCE WILL BE HERE IN THE OFFICE
FOR GLAZE AND POWER OUTAGE REPORTS. WE ARE USING WEBENTRY REPORTS TOO.
THANKS TO ALL FOR YOUR ASSISTANCE. ACCURATE GLAZE THICKNESS REPORTS
ARE GOING TO BE EXCEEDINGLY HELPFUL. WOULD LIKE ON BRANCHES AND
PAVEMENT. ONCE WE SURPASS .25 THICKNESS...INITIAL PROBLEMS BEGIN AND
MAGNIFY GREATLY AT .5 INCH.
WE FORESEE ABOUT 5. TO .9 INCH FREEZING RAIN TODAY IN THE W TWO THIRDS
OF MASSACHUSETTS... THIS PER 00Z/7 GFS ENSEMBLE MEAN QPF MATCHING WELL
AT 06Z FOR THE FIRST 6 HOURS AND THE ONCOMING PLUME. THE VERIFICATION
STARTS AT 06Z THRU 21Z...AS A MATTER OF FACT...WE THINK GLAZE CONTINUES
INTO EARLY THIS WED NIGHT NRN MASS AND S NH.
CONCERN ALSO ABOUT WHAT WIND DOES TO REMAINING GLAZED TREE LIMBS AND
WIRES THURSDAY MORNING.
00Z/EC CONFIRMS ICE ACCUM POTENTIAL VIA ITS SFC TEMPS.
WE ARE CONTINUING WSW AS PLACED FOR THE TIME BEING. THERE WILL BE NO
SHIFT TO AN ICE STORM WARNING SINCE THIS TECHNICALLY SHORTENS LEAD TIME
ON THE VERIFICATION.
MORE DETAILS ON ICE AT 4 AM AS WE NEED TO DIGEST SFC TEMP TRENDS VS GUIDANCE.
MEANWHILE WINTER WX ADVISORY WAS EXPANDED TO THE CAPE AND ISLANDS
EARLIER THIS MORNING.
ICY THIS MORNING. PROBLEMS WITH THE MOS GUIDANCE... BE CAREFUL USING
LITERALLY. UNTIL WE GET DECENT ELY BL MIXING WIND... MODEL MOS GUIDANCE
WILL HAVE PROBLEMS. TONIGHT IT APPEARS 00Z/7 NAM MET MOS IS A LITTLE
BETTER THAN THE MAV MOS GUIDANCE... YET DURING THE THIS PAST TUESDAY
AFTERNOON... THE 2M TEMPS OFF THE GFS WERE BETTER THAN THE NAM. LOTS
OF CONFLICTING DATA TO SORT. NOTING NGM MOS GUIDANCE COLDER!
ALSO...ITS MY EXPERIENCE THAT PSM MOS GUIDANCE CAN BE AN EFFECTIVE
FCST TOOL FOR NRN ESSEX COUNTY AND EVEN SOMETIMES BOSTON.
BOTTOM LINE... THIS IS AN ICY POTENTIALLY QUITE DANGEROUS MORNING.
FORESEE MANY DELAYS ALL UNTREATED SFCS. AND EVEN IF MAIN ROADS ARE
TREATED...THINK OF EVERYONE STEPPING OUTSIDE THEIR HOMES ONTO UNTREATED
SIDEWALKS AND STEPS. NOT GOOD... CANT SEE THE ICY NATURE AS EASILY IN
THE DARK.
SNOW AMOUNTS NOT MATERIALIZING AS ENVISIONED IN MONDAYS FORECASTS BUT
EQUALLY OR MORE SO DANGEROUS THIS MORNING IS THE FREEZING RAIN
ELEMENT!
ALSO IN CLIMO OF BIG POWER OUTAGE EVENTS THIS WINTER...ELEVATION
SNOW STORM OF LATE OCT JUST TO WEST AND SW OF OUR CWA...THE ICESTORM
IN OUR CWA OF EARLY DEC AND NOW WHAT MAY BE DEVELOPING TODAY AND I
THINK WE HAD TWO BIG WIND DAMAGE EVENTS IN OUR CWA THIS FALL.
ONE NOTE...POTENTIAL DAMAGE TODAY SHOULD END UP EXPANDING SWD
SLIGHTLY FROM EARLY DECEMBER. HOW DO WE COMPARE TO THAT EVENT...
DONT HOLD ME TO THIS 100 PCT BUT AS A HELPFUL PREDICTOR... IT SHOULD
NOT BE QUITE AS BAD AS EARLY DECEMBER..PROBABLY A BIT LESS QPF...BUT
POTENTIAL EXISTS FOR LENGTHY POWER OUTAGES PORTIONS OF W HFD COUNTY
ACROSS W 2/3 RDS OF MASS.
A SECOND NOTE: SOME OF US EXPECTED MUCH LONGER DURATION SLEET BASED
ON 25 FOOT THICK BELOW FREEZING LAYER CHANGING RAIN BACK TO ICE.
DIDNT HAPPEN. I9 AM GOING BACK TO RELYING ON -6C = 21F AS THE KEY FOR
ICE PELLETS=SLEET.
&&
.SHORT TERM /10 AM THIS MORNING THROUGH 6 AM THURSDAY/...
WORST OF THE ICING EXPECTED TO BE IN THE BDL-ORH-BED CORRIDOR WHERE
HEAVIER QPF AND LONGER DURATION OF FZRA EXPECTED. LESS ICE FURTHER
NORTH INTO NW MA AND SW NH WHERE MORE SLEET AND LESS QPF EXPECTED.
SREF PTYPE PROBS ALSO HIT THE CENTRAL INTERIOR ZONES HARDER THAN NW
ZONES FOR ICE.
QPF 12-00Z RANGING FROM 0.5" TO 1"+...BUT HEAVIER AMOUNTS EXPECTED
TO BE IN THE COASTAL PLAIN.
SOUNDINGS SHOWING SOME DRYING IN THE LOW TO MID LEVELS WED AFTERNOON
WHICH MAY RESULT IN A LULL IN THE PRECIP.
WINDS...IT APPEARS THE CORE OF THE LLJ WILL REMAIN JET OFFSHORE SO
DO NOT EXPECT VERY STRONG WINDS. BUT GUSTS TO 40 MPH NOT OUT OF THE
QUESTION FOR ACK.
AS COASTAL LOW MOVES NORTH OF THE REGION WED NIGHT...PRECIP WILL
BECOME MORE SHOWERY AND GRADUALLY TRANSITION BACK TO SNOW
SHOWERS...MAINLY NW ZONES. AN ADDITIONAL 1" ACCUM POSSIBLE. WEST
WINDS WILL INCREASE LATE WED NIGHT.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
ONE POSSIBLY TWO WINTRY WEATHER SYSTEMS OF CONCERN DURING THE
EXTENDED TIME FRAME...
THURSDAY...LINGERING CLOUDS AND SCATTERED FLURRIES WILL BE POSSIBLE
AS THE H7 TROUGH AXIS SWINGS ACROSS THE REGION. SEASONABLY COOL AIR
WILL REMAIN.
THURSDAY NIGHT AND FRIDAY...BURST OF FAIRLY STRONG COLD AIR
ADVECTION EXPECTED BEHIND THE DEPARTING LOW. OTHERWISE VERY DRY
CONDITIONS ANTICIPATED. 1000-500MB THICKNESSES DROP INTO THE 510S
WITH H85 TEMPS BETWEEN -13 AND -15 CELSIUS. FORECASTED TEMPERATURES
A FEW DEGREES BELOW MOS GUIDANCE USING A BLEND OF MOS GUIDANCE AND
RAW 2 METER TEMPERATURES. DAYTIME HIGHS FRIDAY SHOULD REMAIN IN THE
20S ACROSS MUCH OF THE REGION.
SATURDAY...DISCREPANCIES EVOLVE REGARDING THE AMPLITUDE OF THE
H5 POLAR LOW AND THE PHASING OF SUBTROPICAL MOISTURE ADVECTING
NORTHEASTWARD FROM THE SOUTHERN PLAINS. THE 12Z GFS AND CANADIAN
GGEM PLACE MORE EMPHASIS ON NORTHERN STREAM SHORT WAVE ENERGY WHILE
THE 12Z ECMWF AND UKMET PLACE MORE EMPHASIS ON A SOUTHERN STREAM LOW.
THE GFS ENSEMBLES FAVOR A BLEND OF THESE OPERATIONAL MODELS TRACKING
SECONDARY LOW PRESSURE JUST SOUTH OF NEW ENGLAND SATURDAY.
USED A BLEND INCLUDING THE 00Z ECMWF AND 12Z GFS WHICH WAS MORE
REPRESENTATIVE OF THE LATEST HPC SOLUTION.
STRONG WARM AIR ADVECTION AHEAD OF A DEVELOPING WARM FRONT IS
EXPECTED TO BRING SNOW ACROSS MUCH OF THE REGION. SNOW MAY MIX
WITH RAIN ALONG THE SOUTH COAST AS BOUNDARY LAYER TEMPERATURES RISE
BEFORE ENDING SATURDAY NIGHT. THERE IS THE POTENTIAL FOR A QUICK SEVERAL
INCHES OF SNOW ACROSS MUCH OF THE AREA DEPENDING ON THE EXACT
LOCATION AND STRENGTH OF SECONDARY LOW REDEVELOPMENT.
GENERALLY CONCENTRATED LOW LIKELY POPS SATURDAY AFTERNOON AND EVENING.
SUNDAY...TURNING DRIER AND MUCH COLDER BEHIND THE DEPARTING LOW.
MAXIMUM TEMPERATURES SUNDAY COULD BE SIMILAR OR SLIGHTLY COLDER
THAN FRIDAYS.
MONDAY...CONTINUED DRY WITH COLDER THAN NORMAL TEMPERATURES.
MONDAY NIGHT AND TUESDAY...NEXT WEATHER SYSTEM OF CONCERN APPROACHES
FROM THE GREAT LAKES WITH SECONDARY LOW PRESSURE FORMING OFF THE MID
ATLANTIC COAST. IT STILL REMAINS TO BE SEEN WHETHER THESE TWO WEATHER
SYSTEMS WILL PHASE INTO A MORE FORMIDABLE LOW. CARRIED A MENTION OF
LOW CHANCE POPS AT THIS TIME.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...
PLS SEE TAFS FOR DETAILS.
AWW`S POSTED EARLIER.
ICESTORM BDL/BAF/ORH ALL MORNING THRU 17Z TO 20Z AT A MINIMUM. PVD FMH HYA
AND ACK HAVE ICE NOW TO IMPROVE FROM SE TO NW THIS MORNING.
MHT SNOW TO ICE TODAY.
CONDS DETERIORATE TO IFR THIS MORNING AND IN MANY PLACES LIFR FOG
DRIZZLE LATE TODAY AS WINDS EASE AND CEILING SETTLES.
WE HAVE CONSIDERED LLWS FOR KACK TODAY...BUT THE GFS AND NAM ARE SO
VASTLY DIFFERENT AT 18Z TODAY... CHECK THIS
GFS NAM
1000 FT 51KT 10KT
2000 FT 67KT 38KT
IFR CONDITIONS ARE EXPECTED TO IMPROVE TO VFR TONIGHT AS LOW
PRESSURE MOVES AWAY FROM THE REGION.
OUTLOOK...THURSDAY THROUGH SUNDAY...
THURSDAY...VFR. SW TO W WIND GUSTS 25-35 KTS.
FRIDAY...VFR. W WIND GUSTS 25-30 KTS DURING THE DAY THEN DIMINISHING.
SATURDAY...AREAS OF IFR CONDITIONS POSSIBLE IN SNOW...POSSIBLY MIXED
WITH RAIN ALONG THE SOUTH COAST.
SUNDAY...VFR. WNW WIND GUSTS UP TO 30 KT.
&&
.MARINE...
OVERNIGHT AND WEDNESDAY...NORTHEAST WINDS INCREASE TO SMALL CRAFT
ADVISORY LEVELS VERY LATE TONIGHT...WITH A PERIOD OF EASTERLY GALES
POSSIBLE WED FOR SE WATERS. WE ARE STILL NOT CONFIDENT SO CONTINUED
GALE WATCH FOR THIS AREA TO ALLOW EXAMINATION OF 00Z MODEL SUITE.
A BREAK IN THE WIND EXPECTED LATE WED/WED EVENING...THEN WEST WINDS
WILL INCREASE AS COASTAL LOW MOVES NORTHWARD AND ANOTHER PERIOD OF
GALES POSSIBLE LATE WED NIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY..
THURSDAY AND FRIDAY...GALES WILL PROBABLY BE NEEDED WITH W WIND GUSTS UP TO
35 TO 40 KT DUE TO STRONG COLD AIR ADVECTION. FREEZING SPRAY POSSIBLE.
SATURDAY...A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED. UNDERCUT WNA
GFS BASED WAVE HEIGHTS AS A 00Z ECMWF/12Z GFS BLEND WAS USED.
SUNDAY...GALE WARNINGS WILL PROBABLY BE NEEDED WITH W WIND GUSTS UP TO 40
KT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
CTZ003-004.
WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR CTZ002.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ002>006-
026.
WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR
MAZ017>024.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
MAZ007-013>016.
WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MAZ008>012.
NH...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NHZ011-012-
015.
RI...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR
RIZ002>007.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
RIZ001.
MARINE...GALE WATCH FROM 6 AM EST THIS MORNING THROUGH LATE TONIGHT FOR
ANZ232-254-255.
SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ231-
233>237-250.
SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS
AFTERNOON FOR ANZ230.
&&
$$
SYNOPSIS...KJC/DRAG/STRAUSS
NEAR TERM...DRAG/BELK
SHORT TERM...KJC
LONG TERM...STRAUSS
AVIATION...DRAG/STRAUSS 255AM
MARINE...KJC/STRAUSS
