Severe Thunderstorm Warning 246, NWS Philadelphia/Mount Holly

000 
WWUS51 KPHI 140300
SVSPHI

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1100 PM EDT WED AUG 13 2008

PAC025-077-089-095-140309-
/O.CAN.KPHI.SV.W.0246.000000T0000Z-080814T0330Z/
LEHIGH PA-NORTHAMPTON PA-CARBON PA-MONROE PA-
1059 PM EDT WED AUG 13 2008

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL MONROE...
SOUTHEASTERN CARBON...WEST CENTRAL NORTHAMPTON AND NORTH CENTRAL
LEHIGH COUNTIES IS CANCELLED...

THE THUNDERSTORM THAT PROMPTED THE WARNING TO BE ISSUED HAS WEAKENED.
THE SEVERE THUNDERSTORM WARNING IS CANCELLED.

LAT...LON 4098 7545 4086 7531 4070 7557 4079 7569
TIME...MOT...LOC 0259Z 228DEG 13KT 4085 7547

$$

RPW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1000 PM EDT WED AUG 13 2008

.SYNOPSIS...
WEAK HIGH PRESSURE AT THE SURFACE WILL GIVE WAY TO LOW PRESSURE
DEVELOPING FROM THE SOUTHWEST TONIGHT, AS UPPER LEVEL LOW PRESSURE
ALSO ACTS ON THE AREA. A LOW PRESSURE CENTER WILL MOVE BY TO THE
SOUTH AND EAST TONIGHT AND EARLY THURSDAY. A FRONT FROM NEW
ENGLAND TO THE EASTERN TENNESSEE VALLEY WILL APPROACH SLOWLY LATER
THURSDAY THROUGH FRIDAY AND MOVE OFF THE COAST FRIDAY NIGHT. HIGH
PRESSURE IS EXPECTED TO MOSTLY PREVAIL OVER THE WEEKEND AND EARLY
NEXT WEEK, BUT ANOTHER FRONT COULD AFFECT THE REGION BY MIDWEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER BERKS/LEHIGH
COUNTIES AND FURTHER W.  WHILE THERE HAS BEEN A GRADUAL WEAKENING
TREND, THE STORMS ARE PULSING AND THE ONES W OF HARRISBURG ARE
HANGING ON AS WELL.  LATEST MSAS DATA SHOWS DECENT INSTABILITY AS
WELL, WHICH INDICATES THESE MAY HANG ON LONGER.  HOWEVER, THE
OVERALL TREND HAS BEEN FOR GRADUAL STABILIZATION AS WELL.
THEREFORE, HAVE INCREASED POPS ACROSS THE NORTHERN AND WESTERN ZONES.
OTHERWISE, CURRENT FCST LOOKS GOOD.

A FEW DISTINCT MECHANISMS WILL AFFECT OUR AREA OVERNIGHT. JUST TO
THE SOUTH OF OUR AREA ARE SOME SHOWERS ASSOCIATED WITH THE CLOSED
LOW MOVING OFF THE CENTRAL MID ATLANTIC COAST.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
A CONTINUATION OF WEAK (OR WEAK-MODERATE) FORCING MECHANISMS IS
FORECAST FOR THURSDAY. BETTER CONVERGENCE AND UPPER WIND FLOW
APPEARS TO AFFECT OUR NORTHERN ZONES, WHERE A 30 POP WAS USED, AND
20 WAS CONTINUED CENTRAL AND SOUTH. THE WEAK SURFACE FRONT OR LEE
SIDE TROUGH DEVELOPING TONIGHT ALSO COULD ACT AS A FOCUSING
MECHANISM FOR OUR WESTERN AND NORTHWESTERN ZONES THURSDAY. THEN,
AS THE UPPER LOW ROTATES SOUTHEASTWARD INTO OUR AREA AND ACTS ON
THE LOW LEVEL CONVERGENT ZONE, FRIDAY APPEARS TO BE A BUSY DAY
CONVECTION-WISE. PROBABILITIES WERE INCREASED SLIGHTLY TO LIKELY
NORTH AND CENTRAL, AND KEPT HIGH CHANCE SOUTH FOR FRIDAY
AFTERNOON AND EVENING. ENHANCED WORDING WAS NOT USED IN THE ZONES
AT THIS TIME, BUT WAS INCLUDED IN THE HAZARDOUS WEATHER OUTLOOK
TO SERVE AS A LEADING INDICATOR.

HIGH TEMPERATURES THURSDAY WERE HEDGED TOWARD THE WARMER GFS AND
NGM MOS WITH PERHAPS A MODERATE AMOUNT OF SUN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
THE FRONT LOOKS LIKE ITS A BIT SPEEDIER TO DEPART THE AREA THAN A
COUPLE OF DAYS AGO, SO THE HIGHER POPS WERE CONFINED TO THE
EVENING PERIOD, WITH JUST A CHANCE OVERNIGHT. WITH SURFACE HIGH
PRESSURE BUILDING, POPS WERE LEFT OUT FOR NOW FOR THE WEEKEND, BUT
IF THE SAME PATTERN HOLDS, I.E. AN UNSTABLE AIRMASS IN A NORTHWEST
FLOW, WE COULD NEED ISOLATED TO SCATTERED AFTERNOON AND EVENING
POPS AT SOME POINT, ESPECIALLY FOR SATURDAY UNTIL UPPER HEIGHTS
BUILD AND THE FLOW FLATTENS A BIT SUNDAY AND MONDAY.

ANOTHER FRONT COULD AFFECT THE AREA BY WEDNESDAY.

HYDROMETEOROLOGICAL PREDICTION CENTER TEMPERATURES AND WINDS WERE
USED LIBERALLY THROUGH THE EXTENDED PERIOD THIS MATCHED GFS MOS
EXTENDED NUMBERS PRETTY WELL FOR MOST TIME PERIODS.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
AN AREA OF LOW PRESSURE OFF THE CAROLINA COAST ALONG WITH A
DISTURBANCE APPROACHING FROM THE WEST WILL CONTINUE TO TOSS SOME
CLOUDS OUR WAY THROUGH TONIGHT. THE MID TO HIGH LEVEL CLOUDS
ACTUALLY THINNED SOME THIS AFTERNOON, WHICH ALLOWED FOR ADDITIONAL
SURFACE HEATING AND CUMULUS DEVELOPMENT. WHILE AN ISOLATED SHOWER
OR STORM WILL POP UP INTO THE EVENING, COVERAGE IS VERY SMALL TO
NOT REALLY INCLUDE AT THE TERMINALS /EXCEPT A VCSH AT KILG AS A
CELL IS NEAR THERE AS OF 1915Z/. AS THE DISTURBANCE NEARS OUR AREA
TONIGHT INTO THURSDAY, THERE IS THE POTENTIAL FOR A SHOWER OR
STORM ONCE AGAIN, HOWEVER COVERAGE WOULD SEEM RATHER SMALL TO
WARRANT A MENTION AT THIS TIME. THE SOUTHERLY FLOW WILL TEND TO
DIMINISH THROUGH THE EVENING AS DECOUPLING OCCURS, HOWEVER THE
SURFACE WINDS WILL BE MORE SOUTHEASTERLY FOR AWHILE THIS EVENING
BEFORE SETTLING DOWN ESPECIALLY AT KACY AND KILG DUE TO A SEA
BREEZE AND BAY BREEZE RESPECTFULLY. REGARDING CLOUD COVER TONIGHT,
WE SHOULD LOSE A GOOD AMOUNT OF THE CUMULUS WITH THE LOSS OF
DAYTIME HEATING HOWEVER SOME MID TO HIGH LEVEL CLOUDS WILL BE
STREAMING ACROSS THE AREA. THERE ARE SOME INDICATIONS THAT SOME
LOW CLOUDS AND FOG DEVELOP AFTER MIDNIGHT, HOWEVER CONFIDENCE IS
RATHER LOW WITH THIS GIVEN THE DIFFERENCES IN THE MODELS. IT
APPEARS THAT DESPITE INCREASING MOISTURE, A WEALTH OF LOW CLOUDS
AND FOG WILL NOT DEVELOP. WE ONLY PLACED SOME FOG AND A MENTION OF
FEW LOWER CLOUDS /MOSTLY MVFR/ IN A TEMPO GROUP AT SOME TERMINALS,
MAINLY BASED ON CLIMATOLOGY. OTHERWISE, VFR CONDITIONS ARE
EXPECTED.

ON THURSDAY, AN UPPER-LEVEL TROUGH WILL BE EDGING CLOSER TO OUR
AREA. THIS IS EXPECTED TO PROMOTE CUMULUS DEVELOPMENT ESPECIALLY
ONCE DAYTIME HEATING GETS GOING. WE MAY SEE SOME ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS POPPING UP, PARTICULARLY CLOSER
TO KABE AND KRDG. AS OF NOW, THIS SHOULD OCCUR AFTER 18Z. A LIGHT
WEST TO NORTHWESTERLY WIND SHOULD INCREASE SOME AND TEND TO SHIFT TO
THE SOUTHWEST BY LATER IN THE DAY AT MOST TERMINALS. A SEA BREEZE
MAY AFFECT KACY WITH PERHAPS A BAY BREEZE ARRIVING AT KILG.

OUTLOOK...
THE UPPER-LEVEL TROUGH AND ASSOCIATED SURFACE FRONT IS FORECAST TO
BECOME BETTER DEFINED ON FRIDAY. THIS SHOULD LEAD TO MORE NUMEROUS
SHOWERS AND THUNDERSTORMS, SOME OF WHICH COULD BE LOCALLY GUSTY.
SOME LOCALIZED FOG WILL BE POSSIBLE EACH LATE NIGHT/EARLY MORNING
THROUGH SUNDAY MORNING. HIGH PRESSURE BUILDS IN FOR SATURDAY AND
SUNDAY, WITH A COLD FRONT GRADUALLY NEARING TOWARD THE MIDDLE OF
NEXT WEEK.

&&

.MARINE...
A SOUTHERLY FLOW GENERALLY 10 KNOTS WILL CONTINUE TO DOMINATE THE
WATERS INTO TONIGHT, ALTHOUGH THE WIND SHIFTED TO SOUTHEASTERLY
EARLIER UP DELAWARE BAY. AN AREA OF LOW PRESSURE WILL MOVE FROM OFF
THE CAROLINA COAST THIS EVENING TO WELL OFF THE NEW JERSEY COAST
OVERNIGHT AND THURSDAY MORNING. THIS WILL ALLOW THE SOUTHERLY FLOW
TO GRADUALLY TURN TO THE NORTH OVERNIGHT AS THE STORM SYSTEM PASSES
TO OUR EAST. DESPITE THE STORM GRADUALLY STRENGTHENING AS IT SLIDES
TO OUR EAST TONIGHT, FORECAST SOUNDINGS INDICATE NOT MUCH IN THE WAY
OF INCREASING SURFACE WINDS AS THE TRUE GRADIENT REMAINS WELL EAST.
THE WINDS WILL THEN SHIFT AROUND TO THE WEST DURING THURSDAY AS WE
LOSE THE INFLUENCE OF THE OCEAN STORM. THE FLOW MAY BECOME WEAK
ENOUGH WHERE IT SHIFTS TO ONSHORE ESPECIALLY NEARSHORE IN THE
AFTERNOON AND CHANNELS UP DELAWARE BAY.

THE NEXT STORM SYSTEM WILL BE APPROACHING ON THURSDAY IN THE FORM OF
AN AMPLIFYING UPPER-LEVEL TROUGH. THIS FEATURE WILL PUSH A FRONTAL
BOUNDARY OUR WAY FRIDAY. THE SOUTHERLY FLOW IS EXPECTED TO INCREASE
AHEAD OF THIS, HOWEVER MODEST AT BEST ATTM AS FORECAST SOUNDINGS DO
NOT HINT AT A WELL PRONOUNCED LOW-LEVEL JET. SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO BECOME MORE NUMEROUS ON FRIDAY, SOME
OF WHICH COULD BE LOCALLY GUSTY. HIGH PRESSURE GRADUALLY BUILDS
TOWARD OUR AREA SATURDAY, THEN SETTLES SOUTH AND EAST SUNDAY INTO
MONDAY. NO HEADLINES ARE ANTICIPATED AT THIS TIME THROUGH THE
PERIOD, AND WE STAYED FAIRLY CLOSE TO CONTINUITY FOR SEAS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

SYNOPSIS...
NEAR TERM...NIERENBERG
SHORT TERM...
LONG TERM...
AVIATION...GORSE
MARINE...GORSE

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
335 PM EDT WED AUG 13 2008

DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-055-
060>062-067>071-142000-
NEW CASTLE-KENT-INLAND SUSSEX-DELAWARE BEACHES-CECIL-KENT MD-
QUEEN ANNES-TALBOT-CAROLINE-SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-
MIDDLESEX-WESTERN MONMOUTH-EASTERN MONMOUTH-MERCER-SALEM-GLOUCESTER-
CAMDEN-NORTHWESTERN BURLINGTON-OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY-
ATLANTIC COASTAL CAPE MAY-COASTAL ATLANTIC-COASTAL OCEAN-
SOUTHEASTERN BURLINGTON-CARBON-MONROE-BERKS-LEHIGH-NORTHAMPTON-
CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
335 PM EDT WED AUG 13 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...NORTHERN
DELAWARE...SOUTHERN DELAWARE...NORTHEAST MARYLAND...CENTRAL NEW
JERSEY...NORTHERN NEW JERSEY...NORTHWEST NEW JERSEY...SOUTHERN NEW
JERSEY...EAST CENTRAL PENNSYLVANIA...NORTHEAST PENNSYLVANIA AND
SOUTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS FRIDAY AND FRIDAY EVENING MAY BE STRONG, AND
PRODUCE HEAVY RAIN, GUSTY WINDS, HAIL, AND DANGEROUS CLOUD TO
GROUND LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

ANZ430-431-450>455-142000-
DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM-
COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM-
COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM-
COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM-
335 PM EDT WED AUG 13 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND
DELAWARE BAY WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS FRIDAY AND FRIDAY EVENING MAY BE STRONG, AND
PRODUCE HEAVY RAIN, GUSTY WINDS, HAIL, AND DANGEROUS CLOUD TO
SURFACE LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
848 PM EDT WED AUG 13 2008

PAZ060-140145-
BERKS PA-
848 PM EDT WED AUG 13 2008

...A STRONG THUNDERSTORM WILL AFFECT BERKS COUNTY...

AT 848 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 13 MILES NORTHWEST OF READING...MOVING NORTHEAST
AT 21 MPH. THE THUNDERSTORM WILL BE NEAR CENTERPORT...SHOEMAKERSVILLE
AROUND 900 PM...LENHARTSVILLE...FLEETWOOD AROUND 915 PM...KUTZTOWN
AND LYONS AROUND 930 PM.

HEAVY RAIN WILL FALL FROM THIS STORM...CAUSING WATER TO POND ON
ROADWAYS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.

THIS STORM MAY ALSO PRODUCE SMALL HAIL.

RPW