Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 272303
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
703 PM EDT SUN JUL 27 2014

.SYNOPSIS...
A RATHER STRONG AREA OF LOW PRESSURE BY JULY STANDARDS WILL DEVELOP
OVER NY AND PA TONIGHT. ITS WARM FRONT WILL BRING A ROUND OF HEAVY
SHOWERS AND THUNDERSTORMS MONDAY MORNING TO THE REGION FOLLOWED BY
POSSIBLE STRONG THUNDERSTORMS MONDAY AFTERNOON TO THE AREA AS ITS
ATTENDING COLD FRONT APPROACHES FROM THE WEST. BY TUE THE FRONT
MOVES OFFSHORE WITH DRY AND MUCH LESS HUMID WEATHER OVERSPREADING
THE REGION AND CONTINUING FOR MUCH OF THE REMAINDER OF THE
WORKWEEK.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...

*** WIDESPREAD HEAVY RAIN AND T-STORMS POSSIBLE LATE TONIGHT INTO
 MONDAY MORNING ***

7 PM UPDATE...

STILL MONITORING CONVECTION OVER WESTERN MA VICINITY OF
SPRINGFIELD. STORMS HAVE A HISTORY OF PRODUCING STRONG WINDS...LARGE
HAIL AND HEAVY RAINFALL. ACTIVITY WILL CONTINUE MOVING EAST-
SOUTHEAST INTO CT WHERE TEMPS REMAIN IN THE L80S WITH DEW PTS IN
THE U60S/L70S. THIS YIELDS ML CAPES OF AROUND 1500J/KG. STORMS
WILL WEAKEN SLOWLY WITH SUNSET HOWEVER MAY PERSIST A WHILE LONGER
GIVEN DEEP LAYER SHEAR OF 35 KT AND MID LEVEL LAPSE RATES OF
6-6.5C/KM.

OTHERWISE REMAINDER OF THE REGION WILL REMAIN DRY. THEN LATER
TONIGHT OUR ATTENTION SHIFTS TO CONVECTION CURRENTLY OVER WESTERN
PA ASSOCIATED WITH ANOMALOUS SHORT WAVE TROUGH AND ASSOCIATED DEVELOPING
LOW PRES AND ATTENDING WARM FRONT. THIS ACTIVITY WILL REACH CT AND
WESTERN MA BETWEEN 06Z-09Z THEN THE REMAINDER OF THE REGION 09Z-
12Z. HEAVY RAIN AND A FEW STRONG STORMS ARE POSSIBLE WITH THIS
NEXT ROUND. EARLIER DISCUSSION BELOW.

==================================================================

ANOMALOUS POTENT SHORT WAVE TROUGH OVER THE GREAT LAKES THIS
AFTERNOON WILL BRING A ROUND OF HEAVY SHOWERS/T-STORMS LATE TONIGHT
INTO MON MORNING...FOLLOWED BY A SECOND ROUND OF T-STORMS /POSSIBLY
STRONG TO SEVERE/ MON AFTERNOON.

AS FOR THIS EVENING...WARM FRONTAL CONVECTION HAS MOVED OFFSHORE AS
OF MID AFTERNOON. SPC MESOANALYSIS INDICATES MUCH DRIER MID LEVEL
AIR OVER NY AND PA ADVECTING EASTWARD TOWARD NEW ENGLAND. THE
LEADING EDGE OF THIS DRIER AIR IS ON THE BACKSIDE OF THE MID LEVEL
TROUGH ACROSS EASTERN NY STATE AND WESTERN NEW ENGLAND. UNTIL THIS
MLVL TROUGH EXITS EAST OF THE AREA THERE IS THE RISK OF AN ISOLATED
TSTM WITH THE HIGHEST RISK ACROSS WESTERN CT/MA INTO SOUTHWEST NH.
ELSEWHERE DRY AND HUMID CONDITIONS SHOULD PREVAIL. GIVEN THE HIGH
DEW PT/THETA-E AIRMASS OVER THE REGION...LOW CLOUDS AND FOG SHOULD
DEVELOP AFTER SUNSET AS THE BLYR COOLS.

OVERNIGHT...INITIAL SHORT WAVE RIDGING AND MID LEVEL DRY AIR SHOULD
KEEP SOUTHERN NEW ENGLAND DRY THROUGH ABOUT 06Z/2AM. THEREAFTER
POTENT SHORT WAVE TROUGH OVER THE GREAT LAKES APPROACHES FROM THE
SOUTHWEST. THIS FEATURE INDUCES CYCLOGENESIS OVER PA/NY STATE. A
BAND OF WARM FRONTAL PRECIP/CONVECTION WILL SWEEP ACROSS THE REGION
BETWEEN 09Z-12Z FROM SW TO NE. HEAVY DOWNPOURS AND A FEW OF THE
STRONGER STORMS MAY CONTAIN GUSTY WINDS AS MUCH OF THE MDL GUID
INDICATES 500-1000 J/KG OF CAPE TOWARD 12Z. HOWEVER THE GREATEST
RISK IS ISOLATED POOR DRAINAGE FLOODING. THINK RISK OF FLASH
FLOODING IS LOW GIVEN HOW QUICKLY SYSTEM IS MOVING AND PWATS ARE
ONLY +1 SD ABOVE CLIMO. NEVERTHELESS HEAVY SHOWERS/TSTMS MAY IMPACT
THE MORNING COMMUTE.

IT WILL BE A WARM AND MUGGY WITH DEW PTS IN THE 60S TO AROUND 70.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
*** FEW STRONG TO SEVERE STORMS POSSIBLE MON AFTERNOON ***

IMPRESSIVE SHORT WAVE TROUGH SWINGS ACROSS THE AREA MON WITH 500 MB
HEIGHTS ON THE ORDER OF -3 SD FROM CLIMO! SURFACE LOW PRES TRACKS
FROM PA/NY BORDER THEN ACROSS CENTRAL NEW ENGLAND IN THE AFTERNOON.
WARM FRONTAL CONVECTION WITH HEAVY RAIN IS LIKELY IN THE MORNING BUT
SHOULD LIFT QUICKLY NORTHEAST AND EXIT THE REGION 12Z-15Z FROM SW TO
NE. WARM SECTOR THEN OVERSPREADS EASTERN HALF OF THE REGION WITH
TEMPS RISING INTO THE 80S AND DEW PTS 65-70. THIS WILL YIELD SB
CAPES OF 1000-2000J/KG ALONG WITH MID LEVEL LAPSE RATES OF 6-6.5C/KM
AS COOLING OCCURS ALOFT. DEEP LAYER SHEAR IS STRONG AS WELL WITH 0-6
KM 35 TO 40 KT. FORCING FOR ASCENT WILL BE PROVIDED BY STRONG
FRONTAL CONVERGENCE AS COLD FRONT APPROACHES FROM THE WEST. IN
ADDITION LFQ OF ANOMALOUS UPPER LEVEL JET OVER THE AREA WILL PROVIDE
ENHANCED QG FORCING. THE ONLY WRINKLE IS THE EXACT TIMING AND
TRAJECTORY OF THE DRY SLOT WHICH MUCH OF THE GUID SUGGEST WILL BE
OVER SOUTHEAST MA AND VCNTY. THUS THE GREATEST THREAT OF STRONG TO
SEVERE TSTMS MAY BE FROM INTERIOR CT NORTHEAST INTO CENTRAL AND
NORTHEAST MA INCLUDING SOUTHERN NH. SPC HAS PLACED THIS REGION IN A
SEE TEXT. MAIN THREATS WILL BE STRONG TO DAMAGING WINDS/LARGE HAIL
AND LOW RISK OF AN ISOLATED TORNADO GIVEN STRONG LOW LEVEL SHEAR AND
HIGH DEW PTS/LOW LCL.

MON NIGHT...

BIG IMPROVEMENT BEHIND THE FRONTAL PASSAGE WITH MUCH LESS HUMID
AIRMASS OVERSPREADING THE REGION WITH DEW PTS FALLING INTO THE 50S!
THIS WILL SUPPORT LOW TEMPS BY TUE MORNING IN THE MU50S INLAND AND
LOW TO MID 60S ALONG THE COAST.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
*/ HIGHLIGHTS...

 - SLIGHTLY COOL AND DRY INTO THE END OF JULY!
 - SCATTERED STORMS POSSIBLE ACROSS INTERIOR NEW ENGLAND FOR THURSDAY
 - DECENT CHANCES FOR WET WEATHER FRIDAY INTO SATURDAY
 - POSSIBLE DAILY OCCURRENCES OF INTERIOR STORMS INTO NEXT WEEK

*/ OVERVIEW AND MODEL PREFERENCE...

INCREDIBLE PATTERN FOR MID-SUMMER! ENSEMBLE SIGNALS AVERAGING WELL-
BELOW NORMAL /-4 TO -5 SD/ FOR BOTH TEMPERATURE AND HUMIDITY ACROSS
THE NE CONUS AS A BUCKLED PATTERN PREVAILS WITH PREFERRED TROUGHING
ACROSS THE GREAT LAKES NEIGHBORED BY STRONG RIDGING. ANTICIPATING A
COOL TO SEASONABLE PATTERN LACKING OF HEAT AND HUMIDITY.

GOING DEEPER...SLIGHTLY NEGATIVE NAO/AO INDICES INTO THE EARLY-HALF
OF AUGUST AS THE ENSEMBLE SPREAD OF THE PNA EXHIBITS AN OVERALL
POSITIVE TREND SIGNALS CONTINUED RIDGING OVER THE E-PACIFIC WITH
PREFERRED TROUGHING E. NO SURPRISE THAT THE NAEFS/GEFS ANALOGS ALONG
WITH THE EC-ENSEMBLE HOLD A BUCKLED PATTERN ACROSS THE REGION AS THE
W-ATLANTIC RIDGE REMAINS STOUT. TREND OF ANOMALOUS BELOW-NORMAL
CONDITIONS PREVAILS.

THOUGH...PER AFOREMENTIONED ANALOGS/ENSEMBLES...THERE IS A POTENTIAL
TREND TOWARDS DEAMPLIFICATION. THIS RESONATES WITHIN GLOBAL FORECAST
SOLUTIONS HIGHLIGHTING A PHASE-SHIFT IN THE MJO CLIMATOLOGICALLY
RESULTING IN A MORE ZONAL PATTERN WITH WARMER TEMPERATURE ANOMALIES
OVER NORTH AMERICA. SOME UNCERTAINTY WITH A CONTINUED LOW ANOMALY
OVER NE CANADA. WILL HAVE TO WAIT AND SEE.

AS TO THE FORECAST...WILL TREND WITH MORE SEASONABLE CONDITIONS AS
CYCLONIC FLOW ALOFT PREVAILS USHERING MUCH COOLER AIR S OUT OF
CANADA. PRECIPITATION CHANCES VARY...BUT WILL NEED TO CLOSELY
MONITOR INDIVIDUAL IMPULSES AND ACCOMPANYING JET STREAKS THROUGH THE
OVERALL TROUGH PATTERN. ITS PLAUSIBLE TO SEE PERIODS OF WET WEATHER
SHOULD THE TROUGH WOBBLE PARENT WITH ITS NEIGHBORING RIDGE AXES.
WILL BREAK DOWN THE HIGHLIGHTS/CONFIDENCE WITHIN THE DAILY
DISCUSSION BELOW.

*/ DAY-TO-DAY DETAILS...

TUESDAY INTO WEDNESDAY...

MID- TO UPPER-LEVEL CYCLONIC FLOW USHERS +8-10C H85 AIR INTO S NEW
ENGLAND AS THE MAJORITY OF ACTIVITY/DYNAMICS IS SHUNTED OFFSHORE.
WEAK HIGH PRESSURE WITH LIGHT WINDS SLOWLY TURNING S TOWARDS THE END
OF THE PERIOD. LOTS OF DRY AIR IN PLACE AS IT CONTINUALLY WRAPS INTO
THE OCCLUSION AS NEW ENGLAND FINDS ITSELF WITHIN THE LFQ OF THE
UPPER-LEVEL JET...A FAVORABLE REGION OF SUBSIDENCE.

WILL PREVAIL WITH SEASONABLE CONDITIONS WITH SEA-BREEZES ALONG THE
SHORES. A DRY FORECAST WITH ACTIVITY HELD WELL N/W PARENT WITH THE
OCCLUSION AND BETTER COLD-POOL. PARTLY CLOUDY CONDITIONS DURING THE
DAY WITH DIURNAL CUMULUS.

THURSDAY...

MAIN IMPULSE ASSOCIATED WITH THE OCCLUSION EJECTS CYCLONICALLY OVER
THE E GREAT LAKES. EXPECT SUBSEQUENT FALLING HEIGHTS COLOCATED WITH
STRONG ENHANCED ASCENT AND DEEP-LAYER LIFT /ESPECIALLY WITHIN THE
LFQ OF AN ATTENDANT JET STREAK/.

SHOULD SEE DIURNALLY-DRIVEN ACTIVITY DEVELOP ACROSS INTERIOR NEW
ENGLAND BENEATH COOLER AIR ALOFT AND CYCLONIC FLOW. SEVERITY SHOULD
BE LIMITED LACK OF INSTABILITY WITH POOR LAPSE RATES AND ABUNDANCE
OF DRY AIR...DESPITE DECENT SW-NE UNI-DIRECTIONAL SHEAR. EXPECT
ISOLATED TO SCATTERED ACTIVITY AWAY FROM THE SHORELINES WHICH SHOULD
REMAIN FAIRLY QUIET UNDER THE INFLUENCE OF ONSHORE MARITIME AIR.

FRIDAY INTO SATURDAY...

PACIFIC-ORIGIN ENERGY ROUNDING THE BROADER TROUGH PATTERN STREAMS NE
ACROSS NEW ENGLAND. MID- TO UPPER-LEVEL TIGHTENING OF THE PRESSURE
GRADIENT RESOLVES A FASTER JET STREAK SUBSEQUENTLY. SHOULD SEE A
BROADSCALE REGION OF FAVORABLE ASCENT DEVELOP ACROSS NEW ENGLAND.

BUT CHALLENGES PREVAIL BETWEEN LIKELY DIURNALLY DRIVEN ACTIVITY
ACROSS INTERIOR NE-CONUS AND LINGERING OFFSHORE FRONTAL BOUNDARY.
ANTICIPATING A REGION BETWEEN OF DRIER WEATHER...JUST WHERE AND HOW
IT EVOLVES ENTERTAINS A FAIR AMOUNT OF UNCERTAINTY.

EC/GEFS TREND WITH ACTIVITY MAINLY ACROSS THE INTERIOR WHEREAS THE
27.12Z GFS RETROGRADES THE OFFSHORE FRONT PARENT WITH A FRONTAL LOW
CONSEQUENTIAL OF THE AFOREMENTIONED PACIFIC ENERGY. ALL SOLUTIONS
SHOW THE MAIN LOW OVER THE GREAT LAKES LIFTING OUT OF THE REGION TO
THE NE.

SUNDAY INTO EARLY NEXT WEEK...

THOUGH PATTERN DEAMPLIFICATION IS POSSIBLE...CYCLONIC FLOW PREVAILS
BEHIND THE EARLIER PACIFIC IMPULSE. WILL HOLD WITH THE TYPICAL
SUMMER-TIME PATTERN OF CONVECTION ACROSS THE INTERIOR WITH QUIET
WEATHER ALONG THE SHORES.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

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

7 PM UPDATE...

ONLY CHANGE TO 18Z TAFS WAS TO ACCOUNT FOR TSTMS VICINITY OF
BAF/BDL THRU 00Z/01Z. OTHERWISE NO CHANGES. EARLIER DISCUSSION
BELOW.

================================================================

MODERATE CONFIDENCE THROUGH MON...THEN INCREASING CONFIDENCE MON
NIGHT.

THRU 00Z...SHOWERS AND SCATTERED TSTMS EXIT EASTERN MA 3PM OR
4PM...THEN ANY NEW CONVECTION SHOULD BE VERY ISOLATED IF AT ALL.
ANY LINGERING MVFR ACROSS EASTERN MA WILL IMPROVE TO LOW END VFR
BY 4 PM.

TONIGHT...MARGINAL MVFR/VFR TO START THEN LOWERING TO MVFR/IFR AS
THE NIGHT PROGRESS AS FOG DEVELOPS. ANOTHER ROUND OF HEAVY SHOWERS
WITH SCT TSTMS DEVELOPS 07Z-10Z FROM SW TO NE. HEAVY RAIN AND
GUSTY WINDS ARE THE MAIN THREATS.

MONDAY...IFR/LIFR IN THE MORNING WITH SCT SHRA/TSTMS LIFTS NE INTO
ME 12Z TO 15Z FROM SW TO NE. THEN LOW END VFR MOST TERMINALS BY
AFTERNOON WITH ANOTHER ROUND OF TSTMS POSSIBLE EXPECT ACROSS RI
AND SOUTHEAST MA WHERE RISK OF SHRA/TSTMS IS MUCH LOWER. A FEW
STRONG STORMS ARE POSSIBLE WITH HEAVY RAIN AND GUSTY WINDS.

MONDAY NIGHT...IMPROVING WEATHER AFTER 03Z OR SO AS COLD FRONT
SWEEPS ACROSS THE AREA ALONG WITH A WIND SHIFT TO THE WNW. ANY
LINGERING SHOWERS/TSTMS ACROSS NORTHERN MA AND SOUTHWEST NH AND
MVFR CONDITIONS WILL IMPROVE TO VFR AFTER 03Z OR SO.

KBOS TAF...MODERATE CONFIDENCE. SHOWERS/STORMS JUST ABOUT OFFSHORE
AS OF 230 PM. LITTLE IF ANY NEW CONVECTION UNTIL 09Z-12Z MON.
LOWERING TO MVFR/IFR TONIGHT IN FOG...THEN IMPROVING TO VFR MON
MIDDAY. A FEW STRONG STORMS POSSIBLE MON AFTN.

KBDL TAF...MODERATE CONFIDENCE. BRIEF MVFR CONDITIONS IN STORMS
THRU 00Z-01Z THEN IMPROVING TO VFR. THEN CONDITIONS LOWER 06Z-09Z
TO MVFR/IFR IN SHOWERS AND TSTMS. HEAVY RAIN AND GUSTY WINDS
POSSIBLE. CONDITIONS IMPROVE TO VFR MON MIDDAY WITH ANOTHER ROUND
OF AFTN T-STORM POSSIBLE. A FEW STRONG STORMS POSSIBLE.

OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE.

TUESDAY AND WEDNESDAY...HIGH CONFIDENCE. VFR WITH LIGHT WINDS
GRADUALLY TURNING S. SEA-BREEZES ALONG THE SHORES.

THURSDAY...MODERATE CONFIDENCE. ISOLATED-SCATTERED SHRA/TSRA
POSSIBLE OVER INTERIOR TERMINALS WITH MIX OF MVFR-IFR CONDITIONS.
SEA-BREEZES ALONG THE SHORES.

FRIDAY...LOW CONFIDENCE. SCATTERED-WIDESPREAD SHRA/TSRA. MAIN FOCUS
ACROSS SE/W/CENTRAL NEW ENGLAND. COULD BE A LULL IN ACTIVITY AROUND
THE BOS-PVD CORRIDOR.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

MODERATE CONFIDENCE THROUGH MON NIGHT

TONIGHT...PATCHY DENSE FOG POSSIBLE. SHOWERS AND TSTMS REDEVELOP
TOWARD DAYBREAK. A FEW STRONG STORMS POSSIBLE ALONG WITH VERY HEAVY
RAIN.

MONDAY...PATCHY DENSE FOG IN THE MORNING BURNS OFF/ERODES BY EARLY
AFTERNOON. EARLY MORNING SHOWERS AND TSTMS TAPER OFF FOLLOWED BY A
NEW ROUND OF SHOWERS/TSTMS MID TO LATE AFTERNOON. A FEW OF THESE
STORMS MAY BE STRONG ALONG WITH HEAVY DOWNPOURS. SSW WINDS MAY
APPROACH 25 KT AS THE AFTERNOON PROGRESSES ESPECIALLY NEAR SHORE.

MON NIGHT...COLD FRONT SWEEPS ACROSS THE WATERS WITH A WIND SHIFT
TO THE WNW ALONG WITH DRY WEATHER AND GOOD VSBY.

OUTLOOK...TUESDAY THROUGH FRIDAY...MODERATE CONFIDENCE.

TUESDAY THROUGH THURSDAY...MODERATE CONFIDENCE. LIGHT WINDS
ASSOCIATED WITH HIGH PRESSURE SHOULD ALLOW FOR TRANQUIL BOATING
WEATHER AS SEAS DIMINISH.

FRIDAY...MODERATE CONFIDENCE. WHILE BOATING CONDITIONS REMAIN
TRANQUIL...WILL SEE INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
DEVELOP ACROSS THE WATERS.

&&

.EQUIPMENT...
OUR DOPPLER RADAR IS DOWN. A TECHNICIAN IS ON THE WAY IN. WE
APOLOGIZE FOR ANY INCONVENIENCE.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 7 AM TO 7 PM EDT
     MONDAY FOR ANZ235-250-254>256.

&&

$$
SYNOPSIS...NOCERA
NEAR TERM...NOCERA
SHORT TERM...NOCERA
LONG TERM...SIPPRELL
AVIATION...NOCERA/SIPPRELL
MARINE...NOCERA/SIPPRELL
EQUIPMENT...NOCERA



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