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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 180744
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
344 AM EDT SAT MAY 18 2013

.SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE PROVIDES MAINLY DRY AND SEASONABLE WEATHER FOR THE
WEEKEND. AN APPROACHING WARM FRONT WILL INCREASE THE CHANCE OF
RAIN SUNDAY NIGHT INTO MONDAY. THE FRONT WILL LIFT NORTH OF THE
REGION EARLY NEXT WEEK AND THEN STALL OVER NEW YORK AND CENTRAL
NEW ENGLAND. WEAK WAVES OF LOW PRESSURE WILL MOVE ALONG THE FRONT
MIDDLE OF NEXT WEEK BRINGING WARMER...MORE HUMID CONDITIONS ALONG
WITH SCATTERED DIURNAL SHOWERS AND POSSIBLY A RUMBLE OF THUNDER.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --
340 AM UPDATE...

MID LEVEL CLOSED LOW MOVING ACROSS ATLANTIC CANADA TODAY WILL
PROVIDE MARITIME HIGH PRES OVER THE GULF OF MAINE. THIS SETUP WILL
PROVIDE MAINLY DRY AND SEASONABLE TEMPERATURES OVER THE AREA
TODAY. THE EDGE OF THE COLD POOL ALOFT WILL CLIP SOUTHEAST NH AND
NORTHEAST MA THIS AFTERNOON. THUS THERE COULD BE AN ISOLATED
SHOWER OR SPRINKLE ACROSS THIS REGION. OTHERWISE DRY WEATHER
PREVAILS. AS FOR POPS...SIDED WITH THE DRIER ECMWF SO MAINLY STUCK
WITH PREVIOUS FORECAST.

THERE WILL BE CLOUDS FROM TIME TO TIME AS MENTIONED ABOVE WITH
INSTABILITY ALOFT ACROSS NORTHEAST MA AND NEARBY SOUTHEAST NH. IN
ADDITION WARM ADVECTION CLOUDS WILL STREAM ACROSS WESTERN MA/CT
AND INTO RI FROM TIME TO TIME.

AS FOR TEMPERATURES...SIMILAR REGIME AIRMASS OVER THE REGION AS
YESTERDAY SO NOT EXPECTING MUCH TEMP CHANGE. HOWEVER COASTAL
COMMUNITIES WILL BE COOLER AS SEABREEZE WILL DEVELOP EARLIER TODAY
THAN FRI. TEMPS WERE DERIVED FROM IN HOUSE BIAS CORRECTED MAV/MET
AND ECMWF.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...

-- Changed Discussion --
TONIGHT...
AN ISOLD SHOWER/SPRINKLE COULD LINGER INTO THE EVENING ACROSS NE
MA AND SOUTHERN NH...OTHERWISE DRY CONDITIONS PREVAIL AS 1030 MB HIGH
SETTLES OVER GEORGES BANK. ANOTHER COOL NIGHT /40S/ GIVEN DRY DEW
PTS FROM GOOD BLYR MIXING SAT AFTN COMBINED WITH LIGHT WINDS.
ALTHOUGH NOT AS COOL AS FRI NIGHT/SAT AM GIVEN MORE CLOUDS ARE
EXPECTED TONIGHT.

AS FOR POPS...SIDED AGAIN WITH THE DRIER ECMWF AS COLUMN STRUGGLES
TO SATURATE ALONG WITH WEAK INSTABILITY AND FORCING FOR ASCENT.
THUS MAINLY A DRY NIGHT.

SUNDAY...
WARM FRONT ACROSS MID ATLC REGION BEGINS TO LIFT NORTHWARD AS MID
LEVEL CLOSED LOW OVER ATLC CANADA DEPARTS SEAWARD. THEREFORE ANY
SUN IN THE MORNING WILL FADE BEHIND INCREASING AFTERNOON
CLOUDINESS. WAA/UPGLIDE BEGINS TO DEVELOP LATE IN THE DAY FROM
WEST TO EAST. THEREFORE HAVE LEANED TOWARD THE DRIER ECMWF AND ITS
LATER ONSET TIME FOR SHOWERS. THUS HAVE FOCUSED CHANCE POPS
LATE IN THE DAY. AS A RESULT BULK OF THE DAY WILL BE DRY.
-- End Changed Discussion --

&&

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

 * CHANCE OF SHOWERS SUNDAY NIGHT INTO MONDAY
 * WARM AND MORE HUMID CONDITIONS WITH PERIODS OF SHOWERS FROM
   LATE TUESDAY THROUGH AT LEAST THURSDAY

OVERVIEW AND MODEL PREFERENCES...
NOTING AN AMPLIFIED BUT PROGRESSIVE PATTERN AS UPPER LEVEL RIDGE
BUILDS ACROSS THE EASTERN U.S. ON SUNDAY. THE UPPER FLOW CONTINUES
TO SHOW SIGNS OF BLOCKING AROUND THE CENTRAL U.S. AS CUTOFF H5
LOW DEVELOPS ACROSS THE UPPER PLAINS STATES AND STALLS BY MID
WEEK. UPPER FLOW ACROSS THE NORTHEAST FLATTENS OUT AROUND LATE
MONDAY OR TUESDAY AS A WARM FRONT APPROACHES. MOST OF THE MEDIUM
RANGE MODELS IN GOOD AGREEMENT IN STALLING THIS FRONT...BUT BIG
QUESTION IS WHERE THIS WILL OCCUR. AT THIS POINT...LOOKS LIKE
CONDITIONS BECOME WARMER AND MORE HUMID STARTING MONDAY THROUGH
LATE NEXT WEEK. WEAK WAVES OF LOW PRES MOVE ALONG THE STALLED
FRONT...SO WILL ALSO SEE SCT SHOWERS FROM TIME TO TIME BUT EXACT
TIMING IS UNCERTAIN. BEYOND LATE WEDNESDAY...MODEL SOLUTIONS WIDEN
OUT ON TIMING THE MOVEMENT OF SURFACE FEATURES AS WELL AS THE
PROGRESSION OF THE CUTOFF SYSTEM.

USED A BLEND OF THE 12Z GFS/00Z ECMWF FOR MOST OF THE PERIOD...
BUT DID START TO LEAN MORE TOWARD THE GFS/EC ENSEMBLES LATE IN THE
PERIOD DUE TO THE TIMING ISSUES.

DETAILS...

SUNDAY-MONDAY...HIGH PRES CENTER WILL SHIFT S ACROSS EASTERN MAINE
AND ACROSS THE WESTERN ATLC ON SUNDAY BRINGING SE-S WINDS BUT
MAINLY DRY CONDITIONS EARLY IN THE DAY. WILL SEE DRY CONDITIONS TO
START OUT BUT CLOUDS WILL INCREASE AS MOISTURE WORKS IN. WARM
FRONT WILL APPROACH OUT OF THE MID ATLC AS THE HIGH SHIFTS E
DURING SUN NIGHT. UPPER LEVEL FLOW BACKS FROM NW TO W DURING
MONDAY INTO MONDAY NIGHT AS THE WARM FRONT STARTS TO STALL EITHER
OVER N MA/S NH OR A BIT FURTHER N. NOTING A WEAK WAVE STARTS TO
FORM ON THE FRONT LATE ACROSS THE EASTERN LAKES/NY STATE. THIS
WILL KEEP A CHANCE FOR SHOWERS FROM SUNDAY NIGHT THROUGH MONDAY
NIGHT.

TUESDAY-THURSDAY...UPPER LEVEL PATTERN FLATTENS OUT ACROSS THE
NORTHEAST U.S. AS THE FRONT HANGS UP SOMEWHERE ACROSS CENTRAL NEW
ENGLAND. WEAK WAVES OF LOW PRES EJECT OUT OF THE UPPER LEVEL
SYSTEM ACROSS THE CENTRAL U.S. AND WORK ALONG THIS FRONT. THIS
WILL BRING PERIODS OF SHOWERY CONDITIONS. FOR NOW...HAVE KEPT THIS
FRONT MAINLY N OF THE REGION WITH GOOD INSTABILITY IN PLACE.
TOTAL TOTALS HEAD UP TO THE LOWER-MID 50S...LIFTED INDICES ARE
WELL BELOW ZERO AS WELL. SO...DEPENDING UPON WHETHER ANY SUN
BREAKS THROUGH THE CLOUDS...COULD SEE WIDELY SCT THUNDER FROM LATE
MORNING INTO THE EVENING HOURS EACH DAY. TUESDAY AND WEDNESDAY
LOOK PRETTY MILD WITH HIGHS IN THE MID 70S TO AROUND 80 ALONG WITH
INCREASING DEWPTS.

MODEL TIMING IS SUSPECT BY THURSDAY NIGHT IN TRYING TO MOVE A COLD
FRONT THROUGH THE REGION.

FRIDAY...LOW CONFIDENCE ON THIS PORTION OF THE FORECAST...BUT DID
LEAN TOWARD WPC GUIDANCE IN SLOWLY BRINGING A COLD FRONT ACROSS
THE REGION WITH HIGH PRES BUILDING IN FROM CENTRAL CANADA.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SUNDAY NIGHT/...MODERATE CONFIDENCE.

HIGH CONFIDENCE FOR VFR CONDITIONS INTO SUN MORNING BUT THEN LOWER
CONFIDENCE ON TIMING OF MVFR CONDITIONS AND SHOWERS LATER SUN.
ISOLATED AFTN SHOWER POSSIBLE TODAY OTHERWISE DRY INTO SUN AM.
THEN CHANCES INCREASE LATER SUN FROM WEST TO EAST AS WARM FRONT
APPROACHES FROM THE SOUTHWEST. SEA BREEZE DEVELOPS EARLIER TODAY
THAN FRIDAY. MODEL GUIDANCE....BASICALLY FOLLOWED AN EVEN BLEND OF
THE 00Z NAM AND GFS.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEABREEZE DEVELOPS EARLIER
TODAY THAN FRI. ISOLATED AFTN/EARLY EVENING SHOWER. OTHERWISE DRY
WEATHER PREVAILS INTO SUNDAY.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF. LOW RISK OF AN ISOLATED
SHOWER THIS AFTERNOON/EARLY EVENING. THEN HIGHER CHANCES OF RAIN MID
TO LATE AFTN SUNDAY.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUNDAY NIGHT THROUGH WEDNESDAY....MVFR-IFR CIGS/VSBYS IN PERIODS
OF LIGHT SHOWERS. PATCHY LATE NIGHT/EARLY MORNING FOG EACH DAY
ESPECIALLY ALONG S COAST. LOW PROB OF THUNDER LATE MORNING
THROUGH THE EVENING MON- WED. MODERATE CONFIDENCE.

&&

.MARINE...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SUNDAY/...HIGH CONFIDENCE.

HIGH PRES SETTLES OVER THE GULF OF ME TODAY AND THEN GEORGES BANK
SUNDAY. THUS LIGHT WINDS EXPECTED TRANQUIL SEAS. VSBY WILL GOOD.
DRY WEATHER PREVAILS WITH JUST A LOW RISK OF SHOWERS LATE SUN
ACROSS THE RI WATERS.

OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...

SUNDAY NIGHT...HIGH CONFIDENCE. LIGHT SE WINDS TO START BECOME S
AND PICK UP BUT REMAIN BELOW SMALL CRAFT CRITERIA. SEAS ALSO
REMAIN BELOW SMALL CRAFT.

SUNDAY NIGHT THROUGH TUESDAY...MODERATE CONFIDENCE. S-SW WINDS
PICK UP WITH GUSTS TO 20-25 KT HIGHEST ACROSS THE SOUTHERN OUTER
WATERS. SEAS BUILD TO 5-7 FT...HIGHEST ON THE OUTER WATERS.

WEDNESDAY...MODERATE CONFIDENCE. WINDS DIMINISH BUT REMAINING
GENERALLY S-SW. SEAS REMAIN AOA 5 FT ON THE SOUTHERN OUTER
WATERS.
-- End Changed Discussion --

&&

.FIRE WEATHER...
DRY CONDITIONS WILL CONTINUE THIS WEEKEND. MINIMUM RELATIVE
HUMIDITIES SATURDAY WILL BE BELOW 30 PERCENT IN THE INTERIOR BUT
WINDS WILL BE RATHER LIGHT. ON SUNDAY...HIGHER RELATIVE
HUMIDITIES ARE EXPECTED...FROM 45 TO 60 PERCENT WITH S-SE WINDS
AROUND 10 MPH.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...NOCERA/THOMPSON
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...EVT
AVIATION...NOCERA/EVT
MARINE...NOCERA/EVT
FIRE WEATHER...