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000
FXUS61 KBOX 232103
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
503 PM EDT THU MAY 23 2013

.SYNOPSIS...
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A COLD FRONT WILL MOVE SLOWLY INTO NEW ENGLAND FRIDAY. LOW
PRESSURE WILL DEVELOP ON THIS FRONT...CAUSING THE SYSTEM TO LINGER
ACROSS THE REGION THROUGH THE WEEKEND. THIS WILL BRING SHOWERS AND
COOLER CONDITIONS...WITH A FEW THUNDERSTORMS POSSIBLE. SOME OF THE
RAINFALL WILL BE HEAVY AT TIMES. CONDITIONS SHOULD IMPROVE ON
MONDAY. DRY WEATHER AND SEASONABLE TEMPS ARE EXPECTED INTO THE
MIDDLE OF NEXT WEEK.
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&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
NUMEROUS SHOWERS AND ISOLD TSTMS WITH LOCALLY HEAVY RAINFALL
MOVING NE ACROSS WESTERN NEW ENG. ENVIRONMENT IS MARGINALLY
UNSTABLE WITH MLCAPES AROUND 500 J/KG WHILE MID LEVEL LAPSE RATES
ARE LESS THAN 6 C/KM. INSTABILITY IS A LIMITING FACTOR FOR SVR WX
DESPITE 30-40 KT 0-6KM SHEAR. NEAR TERM FORECAST OF SIGNIFICANT
SEVERE PARAMETER ALSO SUPPORTS LIMITED SVR POTENTIAL. STILL CANT
RULE OUT AN ISOLD SEVERE STORM...BUT HEAVY RAINFALL IS PRIMARY
CONCERN INTO THIS EVENING ACROSS THE INTERIOR WITH PWATS NEAR
1.7".

TONIGHT...COLD FRONT MOVES SLOWLY EAST FROM CENTRAL NEW YORK AND
WILL APPROACH WESTERN NEW ENG TOWARD DAYBREAK AS MID LEVEL TROF
AMPLIFIES OVER THE GT LAKES. SNE WILL BE UNDER THE RIGHT ENTRANCE
REGION OF THE UPPER JET WHICH WILL PROVIDE GOOD FORCING ACTING ON
HIGH PWAT AIRMASS TO BRING LOCALLY HEAVY RAINFALL TO SNE. SHOWERS
AND ISOLD TSTMS WILL BE ONGOING ACROSS THE INTERIOR IN THE
EVENING...THEN FOCUS WILL SHIFT TO THE COASTAL PLAIN AFTER
MIDNIGHT AS LOW LEVEL JET STRENGTHENS ACROSS SE NEW ENG.
INSTABILITY WILL BE WEAKENING OVERNIGHT AND EVEN ELEVATED
INSTABILITY PARAMETERS ARE MARGINAL. STILL CANT RULE OUT ISOLD
TSTMS GIVEN DEEP SYNOPTIC FORCING...BUT LACK OF INSTABILITY
SHOULD LIMIT RAINFALL RATES. AREAS OF URBAN AND POOR DRAINAGE
FLOODING LIKELY OVERNIGHT IN EASTERN NEW ENG.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH AMPLITUDE TROF FORECAST TO CLOSE OFF OVER THE MID ATLC
REGION ON FRIDAY WITH SOUTHERLY FLOW ALOFT. SFC LOW DEVELOPS ON
THE FRONT WHICH WILL SLOW ITS EWD PROGRESS ACROSS SNE. LOW LEVEL
JET WILL BE SITUATED JUST E OF CAPE COD IN THE MORNING WITH AXIS
OF HEAVY RAINFALL CONFINED TO THE CAPE/ISLANDS...BEFORE MOVING E
IN THE AFTERNOON. HOWEVER...SHOWERS WILL PERSIST ALL DAY ACROSS
MUCH OF THE REGION WITH DEEP MOISTURE AXIS IN PLACE AND SFC WAVE
MOVING ALONG FRONTAL BOUNDARY. IN FACT...THIS HAS A WINTER LOOK
TO IT WITH DECENT LOW LEVEL FRONTOGENESIS AND DEFORMATION AXIS
SETTING UP ACROSS WESTERN NEW ENG NW OF SFC LOW. TEMPS WILL
LIKELY FALL INTO THE 50S OVER NW HIGHER TERRAIN AS FRONT MOVES TO
THE EAST...BUT SHOULD REACH WELL INTO 60S TO AROUND 70 ACROSS SE
NEW ENG WHICH WILL REMAIN E OF THE BOUNDARY FOR MOST OF THE DAY.
THE FRONT SHOULD REACH THE I95 CORRIDOR BY LATE AFTERNOON.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
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HIGHLIGHTS...

* SLOW MOVING UPPER LEVEL SYSTEM WILL KEEP SHOWERS AND COOLER
  TEMPS FOR THE WEEKEND
* IMPROVEMENTS BEGIN ON MONDAY...WITH DRIER BUT COOL CONDITIONS
* MODERATING TEMPERATURES ARRIVE BY LATE NEXT WEEK

OVERVIEW AND MODEL PREFERENCES...
ALL OPERATIONAL MODELS NOW ON BOARD WITH DEVELOPING AMPLIFIED
UPPER LEVEL PATTERN ACROSS THE LOWER 48...WITH DIGGING TROUGHS ON
THE EAST AND WEST COASTS WITH BUILDING RIDGE ACROSS THE CENTRAL
U.S. THROUGH A GOOD PORTION OF THIS PERIOD. H5 CUTOFF LOW DEVELOPS
ACROSS THE MID ATLC THEN SLOWLY MOVES INTO THE REGION THIS
WEEKEND...WITH SURFACE LOW DEVELOPING ALONG SLOWLY MOVING COLD
FRONT. LOWERED CONFIDENCE ON TIMING THE EXIT OF THE LOW...
HOWEVER. BY EARLY NEXT WEEK...THOUGH...SHOULD SEE IMPROVING
CONDITIONS BUT COOL TEMPS. TEMPS START TO MODERATE BY MID WEEK.

WENT ALONG WITH 12Z GFS/00Z ECMWF AND THEIR ENSEMBLES...WHICH IS
PRETTY CLOSE TO THE WPC GUIDANCE.

DETAILS...

FRIDAY NIGHT THROUGH SUNDAY...CONTINUED CLOUDY SKIES WITH SHOWERS
AND COOL TEMPS WILL CONTINUE THROUGH MOST OF THE HOLIDAY WEEKEND.
SURFACE LOW PRES TRAPPED WITH ITS UPPER LEVEL CUTOFF LOW WILL
SLOWLY MOVE ACROSS THE REGION...WITH PERIODS OF HEAVY RAINFALL
ANYTIME DURING THIS TIMEFRAME. CURRENT QPF FORECAST SUGGESTS
POSSIBILITY OF 1-2 INCHES OF GENERAL RAIN WITH THE HIGHEST AMOUNTS
ACROSS THE CT VALLEY AND SW NH. HOWEVER...WITH THE CHANCE OF
THUNDER...COULD SEE LOCALIZED FLOODING ESPECIALLY ACROSS CENTRAL
AND WESTERN AREAS WITH GOOD LOW LEVEL MOISTURE INFLOW. WILL
CONTINUE TO MONITOR FOR POTENTIAL OF FLOODING ALONG RIVERS AND LOW
LYING AREAS.

TEMPS WILL BECOME RATHER CHILLY ACROSS S NH/W MA SAT NIGHT AS LOW
PRES SPINS ACROSS E MA...WITH N-NW WINDS IN PLACE. MOS GUIDANCE
SUGGESTS READINGS FALLING BACK TO THE MID-UPPER 30S ACROSS THE
HIGHER TERRAIN. CAN NOT RULE OUT THE REMOTE POSSIBILITY OF SOME
MIXING OVER THE HIGHEST TERRAIN OF SW NH.

FOR NOW...LOOKS LIKE THE LOW AND UPPER LEVEL SYSTEM WILL SLOWLY
MOVE NE DURING SUNDAY...BUT PRECIP WILL LINGER INTO SUN NIGHT
BEFORE TAPERING OFF FROM SW-NE OVERNIGHT SUN. DAYTIME HIGHS WILL
ONLY BE IN THE 50S THROUGH THE WEEKEND.

MONDAY...TRANSITION DAY AS HIGH PRES BUILDS OUT OF CENTRAL CANADA.
MAY STILL SEE SOME WIDELY SCT SHOWERS ACROSS S NH/NE MA EARLY BUT
WILL PUSH NE. WILL CONTINUE COOL...BUT READINGS SHOULD REACH THE
60S.

TUESDAY-THURSDAY...HIGH PRES WILL SHIFT TO THE MID ATLC COAST THEN
OFFSHORE DURING THIS TIMEFRAME. EXPECT A DRY FORECAST WITH SLOWLY
MODERATING TEMPS.
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&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

OVERVIEW...MODERATE CONFIDENCE.

VARIABLE MVFR/IFR CIGS THIS AFTERNOON WILL TREND TO WIDESPREAD
IFR/LIFR TONIGHT INTO FRI WITH AREAS OF FOG DEVELOPING. SHOWERS
AND SCT TSTMS CT VALLEY AND WESTERN NEW ENG THIS AFTERNOON WILL
EXPAND EAST ACROSS REST OF SNE TONIGHT INTO FRI...WITH FOCUS FOR
HEAVY RAINFALL SHIFTING TO THE COASTAL PLAIN LATE TONIGHT AND FRI
MORNING. LOCALIZED LLWS POSSIBLE LATE TONIGHT CAPE/ISLANDS AS LLJ
STRENGTHENS ACROSS THE REGION.

KBOS TERMINAL...MODERATE CONFIDENCE. EXPECT LOWERING CIGS TO IFR
TONIGHT WITH SHOWERS INCREASING. SCT TSTMS POSSIBLE.

KBDL TERMINAL...HIGH CONFIDENCE. WIDESPREAD SHOWERS AND A FEW
TSTMS THIS AFTERNOON AND EVENING.

OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...

FRIDAY NIGHT THROUGH SUNDAY...LOW TO MODERATE CONFIDENCE. VERY
UNSETTLED PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND
MVFR/IFR CONDITIONS IN SHRA/SCT TSRA/FOG. IMPROVING CONDITIONS
DURING SUNDAY NIGHT FROM SW TO NE.

MONDAY-TUESDAY...MODERATE TO HIGH CONFIDENCE. VFR. LOW PROB OF
MVFR CIGS ACROSS S NH/N MA EARLY MON THEN IMPROVING. LOW
CONFIDENCE ON SEA BREEZE DEVELOPMENT.
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&&

.MARINE...
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FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

HIGH CONFIDENCE THROUGH FRIDAY.

LOW LEVEL JET WILL BRING NEAR SCA GUSTS ON THE WATERS THROUGH
TONIGHT...DIMINISHING WEST OF THE CANAL LATER TONIGHT AS THE LLJ
MOVES TO THE EAST. STRONG LOW LEVEL INVERSION WILL LIMIT GUSTS SO
GALES NOT EXPECTED. PERSISTENT SW FLOW WILL RESULT IN BUILDING
SEAS THROUGH FRIDAY. WINDS WILL DIMINISH ON FRIDAY AS THE LLJ
MOVES E OF THE WATERS. EXPECT LOW VSBYS IN FOG AND LOCALLY HEAVY
SHOWERS. ISOLATED THUNDERSTORMS ARE ALSO POSSIBLE.

OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...

FRIDAY NIGHT...LOW TO MODERATE CONFIDENCE. LOW PRES AND COLD FRONT
WILL SLOWLY CROSS THE WATERS...THEN STALL ALONG THE EASTERN NEAR
SHORE WATERS. EXPECT SW GUSTS UP TO 20 KT EARLY...THEN WILL
DIMINISH. LOW PROB FOR THUNDER. AREAS OF LOW VSBYS IN HEAVIER
SHOWERS AND PATCHY FOG. SEAS WILL REMAIN AOA 5 FT MAINLY OVER THE
OPEN WATERS.

SATURDAY-SUNDAY...LOW CONFIDENCE MAINLY FOR TIMING. AS LOW PRES
STALLS ACROSS E MA/MASS BAY...WILL SEE LIGHT/VRBL WINDS EXCEPT
N-NW OVER THE WESTERN WATERS LATER SAT...WHICH WILL SHIFT TOWARD
THE EASTERN WATERS DURING SUN. SEAS REMAIN HIGH. LOW CHANCE OF
TSTMS SAT-SAT NIGHT. LOW PROB OF GUSTS UP TO 25 KT SUN.

MONDAY-TUESDAY...LOW TO MODERATE CONFIDENCE. WINDS BECOME W WITH
GUSTS UP TO 20 KT MON...THEN DIMINISH MON NIGHT-TUE. SEAS AROUND 5
FT ON THE OUTER WATERS MON...THEN SUBSIDING.
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&&

.TIDES/COASTAL FLOODING...

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RI SOUTH COAST THIS EVENING...
A MODERATELY STRONG SOUTHERLY FETCH OF SURFACE WIND AND INCREASING
LOW LEVEL JET IS EXPECTED TO DRIVE ENOUGH WATER INTO NARRAGANSETT
BAY FOR A SURGE AROUND OR EVEN JUST ABOVE A FOOT AT THE TIME OF
THE EVENING HIGH TIDE...ABOUT 2330Z. THIS WILL BE ON TOP OF A
PARTICULARLY HIGH SPRING TIDE. BOTH THE ESTOFS AND ETSS SURGE
GUIDANCE DEPICT ESSENTIALLY NO SURGE THIS EVENING BUT SEEMS LIKE
TOO MUCH OF A S TO SW WIND TO AVOID SOME SURGE...AND AT 15Z PVD
WAS ALREADY SHOWING A .4 FT SURGE AND CLIMBING. IN ADDITION...
SHORELINE FLOODING COULD BE EXACERBATED SOME BY ANY HEAVY RAIN
PRODUCING FRESH WATER RUNOFF THAT STRUGGLES TO DRAIN AT THE
SHORELINE DURING HIGH TIDE.

EAST COAST OF MA THIS WEEKEND...
ASTRONOMICAL HIGH TIDES WILL OCCUR THIS WEEKEND INTO EARLY NEXT WEEK.
WITH SURFACE LOW WOBBLING OVER SOUTHERN NEW ENGLAND SATURDAY AND
INTO SUNDAY...EXPECT GUSTY NORTHERLY TO NORTHWEST WINDS ESPECIALLY
DURING THE DAYTIMES HOURS. AT BOSTON...A HIGH TIDE OF 11.9FT WILL
OCCUR ON FRIDAY NIGHT AT 11:21 PM AND 12.2 FT EARLY SUNDAY
MORNING AT 12:12 AM. EXPECT A LIGHT SOUTHERLY WINDS DURING THE
FRIDAY HIGH TIDE SO THIS IS LESS THAN A CONCERN. LOOKING AT THE
SUNDAY MORNING HIGH TIDE...NORTHERLY TO NORTHWESTERLY WINDS MAY
HELP INCREASE THE SURGE ESPECIALLY FOR CAPE COD BAY. RIGHT NOW
ONLY EXPECT MINOR SPLASHOVER ACROSS NORTH FACING BEACHES. WILL
NEED TO CONTINUE TO MONITOR AND UPDATE WITH THE LATEST FORECAST
GUIDANCE.
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&&

.BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE.
MA...NONE.
NH...NONE.
RI...COASTAL FLOOD ADVISORY UNTIL 9 PM EDT THIS EVENING FOR RIZ002-
     004>007.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT FRIDAY FOR ANZ232.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ233-234.
     SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ230-
     236.
     SMALL CRAFT ADVISORY UNTIL 4 AM EDT FRIDAY FOR ANZ231-251.
     SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ235-237.
     SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR ANZ250.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ254>256.
-- End Changed Discussion --

&&

$$
SYNOPSIS...KJC/EVT
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...EVT
AVIATION...KJC/EVT
MARINE...KJC/EVT
TIDES/COASTAL FLOODING...THOMPSON