Report Created From Product: AFDBOXMA
FXUS61 KBOX 311902
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
302 PM EDT FRI JUL 31 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OFF THE EASTERN SEABOARD...KEEPING THE
REGION IN A WARM AND HUMID AIRMASS THROUGH AT LEAST EARLY NEXT WEEK.
SEVERAL WEAK FRONTS WILL PUSH ACROSS THE REGION...EITHER DISSIPATING
ACROSS THE WATERS OR PUSHING BACK TO THE NORTH. EACH FRONT WILL
BRING THE CHANCE OF SHOWERS AND THUNDERSTORMS...SOME WITH VERY HEAVY
RAINFALL AND A LOW PROBABILITY OF SEVERE WEATHER.
&&
.NEAR TERM /UNTIL 3 AM SATURDAY MORNING/...
MAIN FORECAST CONCERNS FOR TODAY AND TONIGHT REVOLVE AROUND THE
POTENTIAL FOR HEAVY RAINFALL AND SEVERE THUNDERSTORMS.
223PM: EXPANDED FFA SWD INTO HFD COUNTY/TOLLAND COUNTY BASED ON NEW
LINE...HIGH PWATS AND THIS MORNINGS NRLY 2INCHES OF RAIN IN HFD
COUNTY.
1250 PM: UPDATED FOR FFA NW MASS AND SW NH WHERE EXCESSIVE RAIN JUST
OCCURRED ABOUT 36 HOURS AGO AND THE ONCOMING EXCESS HEADING THERE
NOW.
NOON...NO SIGNIFICANT CHANGE IN FCST THINKING. RFALL NR 2 INCHES IN A
FEW SPOTS OF HFD COUNTY THIS MORNING BUT NOW LETTING UP. RERBDL
POSTED. ZONES AS POSTED LOOK REASONABLE TO ME.
1030AM: FLOOD ADVISORY POSTED. BRIEF RFALL RATES MAY BE NEAR 3
INCHES/HOUR BUT ACTUAL HOURLY RFALL OF AROUND 1.3 INCHES. THIS DUE TO
FAIRLY FAST NEWD MOVEMENT.
938 AM: SKYWARN IN THE OFFICE AT 11AM TO ASSIST IN ANY SVR/FF REPORTS
ETC. PUBLIC PRODUCTS UPDATED FOR SHOWERS AND HEAVY THUNDERSTORMS THIS
MORNING IN THE INTERIOR.
912AM: PREV FCST LOOKS GOOD. ANALYZING 12Z OKX SOUNDING AND 03Z SREF
PROBS FOR CAPE...1 INCH RAINS...06Z GEFS PROBS FOR 1 INCH RAINS AND
THE 06Z GFS/NAM/00Z RGEM/GGEM/UK/EC... I DONT THINK MUCH IF ANY SVR
HERE TODAY DUE TO CLOUD CVR/SHOWERS AND LACK OF INSTABILITY..
COULD SEE SMW STORMS E COASTAL EMA ARD 18Z-21Z AND IF WE ARE TO GET
SVR...I THINK CONFINED TO CT RI 16Z-21Z.
AS FOR FLOODING POTENTIAL RAINS...FIRST BATCH NYS/VT TO CENTRAL PA AND THE
EVENING BATCH I THINK S COAST OR SOUTHWARD TOWARD BETTER INSTABILITY.
WILL UPDATE AS NEEDED... PLS MONITOR SWODY1 AND SWOMCD'S.
FROM THE 4AM DISCUSSION BELOW:
A SHORT WAVE TROUGH WILL APPROACH FROM THE WEST TODAY...AND WILL
RESULT IN RAPIDLY INCREASING CLOUDS THIS MORNING AND INCREASING
CHANCES OF SHOWERS FROM WEST TO EAST. AS THE LOW LEVEL JET INCREASES
FROM THE SOUTHWEST...HIGH DEWPOINTS WILL QUICKLY ADVECT NORTHWARD
INTO SOUTHERN NEW ENGLAND ONCE AGAIN. INTRODUCED CHANCE POPS FOR
SHOWERS STARTING THIS MORNING IN THE WEST...INCREASING QUICKLY TO
LIKELY AND CATEGORICAL BY EARLY AFTERNOON PRETTY MUCH EVERYWHERE.
HELD OFF ON ISSUING A FLASH FLOOD WATCH FOR NOW...BASICALLY FOLLOWING
THE REASONING OF THE PREVIOUS SHIFT. PWATS WILL INCREASE ABOVE 2
INCHES PRETTY RAPIDLY TODAY. THEREFORE...SHOWERS AND THUNDERSTORMS
WILL CERTAINLY BE CAPABLE OF PRODUCING TORRENTIAL DOWNPOURS AS THE
AFTERNOON PROGRESSES...AND WILL ALMOST CERTAINLY RESULT IN MINOR
URBAN AND SMALL STREAM FLOODING. HOWEVER...THE FOCUS FOR SERIOUS
FLASH FLOODING DOES NOT SEEM COMPLETELY CLEAR RIGHT NOW. THE HEAVIEST
RAINS MAY COME IN TWO WAVES...ONE ACROSS THE WESTERN/NORTHERN ZONES
THIS AFTERNOON...BUT THAT FOCUS MAY SHIFT AWAY FROM THAT REGION THIS
EVENING AS MORE ROBUST CONVECTION POTENTIALLY MOVES FROM THE NJ/NYC
AREA AND ACROSS OUR SOUTHERN ZONES. THE MID LEVEL FLOW WILL INCREASE
MARKEDLY TODAY AND THE SYSTEM LOOKS TO BE QUITE TRANSIENT. IN
ADDITION...MUCH OF SNE ESCAPED THE REAL HEAVY RAINS FROM THE LAST
SYSTEM. THEREFORE...AT THIS TIME WE ARE HOLDING OFF ON ANY FLASH
FLOOD WATCH ISSUANCE'S. THAT SAID...ISOLD FLASH FLOODING IS NOT OUT OF
THE QUESTION LATER TODAY AND TONIGHT. THE DAY SHIFT MAY BE ABLE TO
BETTER GAGE THE POTENTIAL THIS MORNING AND HAVE PLENTY OF TIME TO
ISSUE A WATCH IF NECESSARY.
THE SEVERE WEATHER POTENTIAL IS ALSO QUITE NEBULOUS AT THIS TIME.
DESPITE THE EXPECTED SURGE OF LOW LEVEL MOISTURE THIS
AFTERNOON...RAPIDLY INCREASING CLOUDS AND OVERSPREADING PRECIP WILL
SERIOUSLY HAMPER INSTABILITY TODAY. HOWEVER...AFTER LOOKING THROUGH
ALL OF THE AVAILABLE GUIDANCE...THERE IS A CHANCE THAT A PORTION OF
THE REGION MAY HAVE A CHANCE TO SEE ISOLD SVR TSTMS TODAY. THE MOST
LIKELY AREA APPEARS TO BE ACROSS CT AND IMMEDIATELY ADJACENT AREAS OF
MASS AND RHODE ISLAND. THIS IS WHERE A PLUME OF RELATIVELY HIGH
THETA-E AIR WILL LIKELY EXIST AND BE JUXTAPOSED WITH A RIBBON OF
MODERATE DEEP LAYER SHEAR BY MID TO LATE AFTERNOON. IT IS IN THIS
AREA WHERE SFC WINDS COULD LOCALLY BACK AS WELL...ENHANCING LOW LEVEL
SHEAR/HELICITY. THEREFORE...A CONDITIONAL THREAT FOR ISOLD DAMAGING
WINDS/TORNADO EXISTS IN THIS AREA...WITH THE CONDITION BEING THE
DEVELOPMENT OF ENOUGH SURFACE-BASED INSTABILITY TO SUPPORT
STRONG/DISCRETE UPDRAFTS. IF ANY CONVECTION THAT DEVELOPS IS NOT ABLE
TO BECOME SFC-BASED THEN ANY SVR THREAT WOULD BE QUITE LOW.
OVERALL...LOW PROB.
&&
.SHORT TERM /3 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SHOWERS AND THUNDERSTORMS...SOME HEAVY WILL BE ONGOING THIS EVENING
ACROSS MUCH OF SOUTHERN NEW ENGLAND. THE THREAT FOR SHOWERS/TSTMS
WILL DIMINISH/END FROM NW TO SE DURING THE NIGHT...WITH THE ACTIVITY
LINGERING ACROSS SOUTHEAST MASS THROUGH EARLY SATURDAY MORNING.
SATURDAY SHOULD BE A PRETTY NICE DAY...A BIT HUMID BUT PLENTY OF SUN.
NAM IS ADVERTISING A FEW POP-UP SHOWERS/TSTMS...BUT KEPT THE FORECAST
DRY FOR NOW AS A WELL-DEFINED TRIGGER SEEMS TO BE LACKING AT THE
TIME. TOOK A BLEND OF THE MAVMOS AND METNAM GUIDANCE FOR MAXES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
RIDGE MOVES EAST OF US SATURDAY NIGHT WITH WEAK EAST SURFACE FLOW.
MOIST LAYER BELOW 700 MB BUT DRY AT THE CIRRUS LEVEL. DEWPOINT
LINGER IN THE 60S. NAM SHOWS LIGHT MEASURABLE QPF OVERNIGHT...BUT
WITH THE LACK OF DEEP MOISTURE OR INSTABILITY OR SIGNIFICANT LIFTING
MECHANISMS WE SUSPECT THIS IS MORE OF A REFECTION OF POTENTIAL
FOG/DRIZZLE. EXPECTING FAIR WEATHER WITH INCREASING FOG AND STRATUS
OVERNIGHT.
COLD FRONT MOVES INTO WESTERN/CENTRAL NEW YORK SUNDAY SUPPORTED BY
UPPER SHORTWAVE. NAM AND GFS AGREE ON FRONTAL PLACEMENT...BUT
DIFFER ON OTHER DETAILS. NAM IS SLOW AND WEAK ON DEVELOPING
INSTABILITY OVER SOUTHERN NEW ENGLAND...THE GFS IS MORE ROBUST.
BOTH MODELS BRING A PRIMARY UPPER JET ACROSS WESTERN PA/CENTRAL
NY...THE GFS HOLDS ONTO THIS WHILE THE NAM DEVELOPS A SECONDARY JET
MAX ALONG THE MID ATLANTIC BLUE RIDGE AREA AND BRINGS A LINKED JET
AREA...RIGHT ENTRANCE OF ONE AND LEFT EXIT OF THE SECOND...ACROSS
EASTERN NY BY LATE DAY AND INTO NORTHERN NEW ENGLAND SUNDAY NIGHT.
COMMON GROUND OF THE TWO WOULD INDICATE HIGHER CONVECTIVE POTENTIAL
IN WESTERN NEW ENGLAND WITH FOCUS ON THE AFTERNOON/EVENING.
BOTH NAM AND GFS INDICATE THE ACTUAL COLD FRONT MOVING ACROSS DURING
MONDAY...KEEPING US IN AN AREA OF LOW LEVEL CONVERGENCE WHILE THE
ENTRANCE REGION OF THE UPPER JET MOVES OVERHEAD AND UP ALONG THE
FRONT. DYNAMIC FORCING AND INSTABILITY ARE THERE...DEWPOINTS REMAIN
IN THE 60S BUT VERTICAL MOISTURE FIELDS ARE FORECAST AS SHALLOW.
WILL FORECAST SLIGHT CHANCE POPS ALONG AND EAST OF THE FRONT
MONDAY...RI AND EASTERN MASS...WITH CHANCE POPS ALONG THE COAST.
ANOTHER COLD FRONT MOVES THROUGH LATE TUESDAY/TUESDAY NIGHT. WILL
GO WITH CHANCE POPS WITH PASSAGE. THE FRONT STALLS SOUTH OF NEW
ENGLAND MIDWEEK WITH WEAK HIGH PRESSURE MOVING OVERHEAD
WEDNESDAY-THURSDAY.
TEMPERATURES ARE BASED ON A BLEND OF MOS.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
THIS AFTERNOON...PLS SEE TAFS FOR DETAILS. NW WIND SHIFT G25-28 KTS
WDSPRD HUD VALLEY TO BDL CEF AT 19Z SPREADING SEWD. MAY ALLOW ENHANCEMENT
OF TSTMS IN N CT AND RI THRU 21Z. IFR/LIFR IN HEAVY SHWRS/TSTMS.
TONIGHT...IFR CONDS LIKELY AS COLD FRONT PUSHES INTO THE REGION WITH
CONTINUING SHOWERS AND TSTMS. SOME IMPROVEMENT IN CIGS/VSBYS SEEN
FROM NORTHWEST TO SOUTHEAST LATE.
SATURDAY...MAINLY VFR EXPECTED.
OUTLOOK /SATURDAY THROUGH TUESDAY/...
SATURDAY NIGHT-SUNDAY...AREAS OF IFR WITH LOCAL LIFR CIGS/VSBYS IN
EARLY MORNING FOG. SHOWERS/SCT TSTMS DEVELOP ACROSS CENTRAL AND
WESTERN AREAS AFTER 17Z AHEAD OF COLD FRONT. SOME WILL HAVE LOCALLY
HEAVY RAINFALL.
SUNDAY NIGHT-MONDAY...LOCAL MVFR-IFR CIGS/VSBYS WITH CONTINUED
CHANCE OF SHOWERS/TSTMS THROUGH SUNDAY NIGHT...THEN A FEW SHOWERS
OVER E AREAS INTO MONDAY. AREAS OF LATE NIGHT/EARLY MORNING FOG WITH
LOCAL IFR-LIFR CIGS/VSBYS.
MONDAY NIGHT-TUESDAY...EARLY MORNING FOG WITH LOCAL MVFR-IFR
CIGS...OTHERWISE VFR. SCT SHOWERS/TSTMS DEVELOPING FROM W-E DURING
THE AFTERNOON...LOCAL MVFR-IFR CIGS/VSBYS...SOME WITH LOCALLY HEAVY
RAINFALL.
&&
.MARINE...
SCA EXPANDED TO ALL COASTAL WATERS THIS AFTN PER SOUTH GUSTS 25 TO 30
KNOTS NOW TO 21Z.
OTRW 5 TO 6 FOOT SWELLS WILL LIKELY PERSIST INTO SATURDAY ACROSS THE
SOUTH COASTAL WATERS. NOTED SOME MODEL DATA POINTING AT THE POTENTIAL
FOR 25 KNOT WIND GUSTS NEARSHORE TODAY...BUT TEMPERED THAT SINCE SW
FLOW OFF THE COLDER WATER MAY LIMIT GUSTS. SHOWERS AND THUNDERSTORMS
WILL BECOME QUITE NUMEROUS OVER THE WATERS...ESPECIALLY THE SOUTH
COAST...BY LATE AFTERNOON AND ESPECIALLY TONIGHT. THIS MAY LEAD TO
LOCALLY HIGHER WINDS AND SEAS AS WELL AS SIGNIFICANTLY REDUCED VSBYS.
OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...
WINDS WILL BE AT OR BELOW 20 KNOTS THROUGH THE PERIOD. MOST OF THE
COASTAL WATERS WILL ALSO HAVE SEAS BELOW 5 FEET THROUGH THE PERIOD.
EXCEPTION IS RI SOUND SATURDAY NIGHT AND THE SOUTHERN OUTER WATERS
THROUGH SUNDAY/ SUFFICIENT SOUTH SWELL ON THE SOUTHERN OUTER WATERS
TO KEEP SEAS THERE AT 5-6 FEET THROUGH SUNDAY. 5 FOOTERS MAY RETURN
FOR A TIME ON THE OUTER WATERS MONDAY AS WELL.
&&
.HYDROLOGY...
FFA ISSUED. SUPPLEMENTS PREVIOUS FLOOD ADVISORY. CONCERN NEAR ROWE
MASS WHERE VERY HEAVY RAIN OCCURRED ABOUT 36 HRS AGO AND ALSO
HILLSIDE THIS AREA.
PLEASE SEE NEAR TERM DISC ABOVE FOR DETAILS ON HYDRO THOUGHTS. BOTTOM
LINE IS THAT QPF VALUES BETWEEN 0.5-1.5 INCHES WITH ISOLATED HIGHER
AMOUNTS OF 3-4 INCHES EXPECTED TODAY AND TONIGHT. THIS FCST IS
SREF/GEFS/PWAT BASED INCORPORATING 700MB FLOW.
1135 AM REPORT 1.9 INCHES NEAR CANTON CT.
RERBDL SEE BELOW AND OR STMT.
&&
.CLIMATE...
RERBDL POSTED FOR THE DAILY BDL RECORD RFALL ON JULY 31.
PLEASE SEE PUBLIC INFORMATION STATEMENT ISSUED AT 612 PM ON WED JUL 29 FOR
DETAILS ON BOTH JULY AND COMBINED JUNE-JULY CLIMATOLOGY FOR OUR FOUR
CLIMATE SITES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR CTZ002-003.
MA...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR MAZ002-003-
008>011.
NH...FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR NHZ011.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
ANZ230>234-236-250-251.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM EDT
SATURDAY FOR ANZ235-237-254>256.
&&
$$
SYNOPSIS...EKSTER
NEAR TERM...DRAG/EKSTER
SHORT TERM...DRAG/EKSTER
LONG TERM...WTB
AVIATION...WTB/DRAG/EKSTER 302P
MARINE...WTB/DRAG/EKSTER
HYDROLOGY...
CLIMATE...
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