Tuesday/Tuesday night

[famartin]

Looks interesting... 50+ knots almost right to the surface:

[Boch23]

For what its worth:

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0229 AM CDT SUN SEP 16 2012

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS NY TO SRN

APPALACHIANS/PIEDMONT REGIONS...

...SYNOPSIS...

SUBSTANTIAL MID-UPPER PATTERN CHANGE IS UNDERWAY AND WILL OCCUR IN

EARNEST DAY-2. SHORTWAVE TROUGH NOW OVER FAR W TX AND NRN CHIHUAHUA

WILL PHASE WITH NRN-STREAM TROUGH...AMIDST BROAD REGIME OF HEIGHT

FALLS. BY START OF PERIOD...FULL-LATITUDE/SYNOPTIC-SCALE TROUGH

SHOULD EXTEND FROM HUDSON BAY ACROSS LS AND MS VALLEY. THIS FEATURE

WILL SHIFT EWD TO LH...OH...TN VALLEY REGION AND N-CENTRAL GULF BY

19/12Z. STRONGEST EMBEDDED SHORTWAVE TROUGH IS FCST TO PIVOT

CYCLONICALLY FROM SERN IA/NRN MO REGION ACROSS SRN IL TO ERN OH/WRN

PA.

PRECEDING THAT PERTURBATION...STG SFC COLD FRONT SHOULD BEGIN PERIOD

OVER PORTIONS OH...MID-ERN TN...AL AND NWRN GULF...REACHING WRN

NY...WRN PA...WV...WRN GA AND CENTRAL/WRN FL PANHANDLE BY 19/00Z.

BY END OF PERIOD...FRONT SHOULD EXTEND FROM ERN QUE ACROSS COASTAL

MID-ATLC OR SRN NEW ENGLAND...SSWWD TO NRN FL. UNCERTAINTIES IN

FRONTAL SPEED GROW WITH TIME AFTER MIDDLE OF PERIOD...IN STEP WITH

GREATER SPREAD IN PROGS REGARDING EJECTION PHASE SPEED OF MAIN

EMBEDDED SHORTWAVE.

...NY TO SRN APPALACHIANS/PIEDMONT REGIONS...

CORRIDOR OF CONVECTIVE DAMAGING-WIND POTENTIAL IS EXPECTED TO SHIFT

EWD ACROSS OUTLOOK AREA FROM MORNING THROUGH AFTN AND AT LEAST INTO

MID-LATE EVENING.

BUOYANCY IS EXPECTED TO INCREASE WITH EWD EXTENT IN PROXIMITY TO

HIGHER BOUNDARY-LAYER MOISTURE NEAR ATLC COAST. MEANWHILE...DEEP

SHEAR AND FRONTAL FORCING GENERALLY WILL BE GREATER WITH NWD

EXTENT...AND WILL SPREAD OVER MORE OF WARM SECTOR WITH TIME.

INSTABILITY WILL BE VERY LIMITED OVER CENTRAL/NRN APPALACHIANS

REGION EWD INTO MID-ATLC. FCST SOUNDINGS REASONABLY SUGGEST

INFLOW-LAYER MLCAPE FOR PRIMARY CONVECTIVE BAND REMAINING BELOW 1000

J/KG MUCH OF PERIOD...AND BELOW 500 J/KG EARLY IN PERIOD AND FROM

PA/SRN NY NWD. HOWEVER...COMBINATION OF WEAK CINH AND STG FRONTAL

FORCING SHOULD YIELD NARROW...PROBABLY LOW-TOPPED BAND OF CONVECTION

MOVING EWD ACROSS INTERIOR MID-ATLC. THOUGH TIMING OF ITS COASTAL

APCH WILL BE AFTER DARK...CONVECTION WILL BE MOVING INTO HIGHER

LOW-LEVEL THETAE...AND MAY BE SUSTAINED AT SVR LEVELS INTO SOME OF

OVERNIGHT HOURS.

ONE COMPLICATING FACTOR MAY BE PRESENCE OF BAND OR CLUSTERS OF

CONVECTION ONGOING EARLY IN PERIOD...RELATED TO INTENSE LOW-LEVEL

WAA/MOISTURE TRANSPORT BELT OVER PORTIONS WRN VA/NC...ERN TN AND/OR

NRN GA. WHILE MUCH OF THIS ACTIVITY LIKELY WOULD OCCUR ATOP

RESIDUAL REGIME OF COOL/DAMMING AIR...STG LOW-LEVEL THETAE ADVECTION

WILL ERODE THAT REGIME WITH TIME AHEAD OF TSTMS. CONVECTION WILL

SHIFT NEWD FROM THOSE AREAS INTO AT LEAST MRGL BOUNDARY-LAYER

INSTABILITY ACROSS CAROLINAS/VA...WHILE ADDITIONAL ACTIVITY MAY

DEVELOP IN FAVORABLE MOIST/DIABATICALLY HEATED AIR MASS OVER PARTS

OF SC/GA. TIMING/PLACEMENT OF SRN/WRN PORTION OF SVR THREAT

THEREFORE IS QUITE UNCERTAIN...BUT UNCONDITIONAL PROBABILITIES

SUPPORTING CATEGORICAL OUTLOOK ARE DRAWN OVER PORTIONS CAROLINAS/GA

IN DEFERENCE TO FCST OVERLAP OF FAVORABLE MOISTURE AND DEEP SPEED

SHEAR.

[phlwx]

Robust 850's FTW!

[phlwx]

Looking at this a bit this morning, looks a lot like a more dynamic and nighttime version of last Saturday. Rain won't be the biggest threat with this, IMO.

[Eskimo Joe]

Hello autumn!

[Parsley]

Hello autumn!

Yup.

[LMolineuxLM1]

Chase car down, needs to be repaired some dumb chick who was delivering food cut over the double yellow lines on a local road close to home and smack my mirror off the housing is still there but the mirror is smashed. So no chasing for me.

[NaoPos]

Strong wording from the spc:

WRN NEW ENGLAND TO NERN GULF COAST...

NARROW LINE OF CONVECTION SHOULD DEVELOP EARLY IN PERIOD AND CROSS

MID-ATLC AND CENTRAL PIEDMONT REGIONS...WITH DAMAGING WIND BEING

PRIMARY THREAT. A FEW TORNADOES ALSO ARE POSSIBLE.

AT START OF PERIOD...MORE THAN ONE BAND OR CLUSTER OF TSTMS MAY BE

ONGOING...MOST LIKELY OVER SRN APPALACHIANS REGION AND OVER ERN

OH/WRN PA AREA. AS EACH MOVES INTO PROGRESSIVELY HIGHER-THETAE AIR

MASS...SVR POTENTIAL WILL INCREASE...WHILE EVOLUTION OF MORE UNIFIED

SQUALL LINE IS EXPECTED. FLOW ALOFT WILL BE MOSTLY PARALLEL TO

CONVECTIVE FORCING...INDICATING RAPID DEVELOPMENT OF LINEAR MODE

THAT WOULD BE MAINTAINED THROUGH PERIOD. OVER MID-ATLC REGION...SFC

LOW SHOULD LIFT NEWD FAST ENOUGH TO OUTPACE NWD EXTENT OF FAVORABLE

DESTABILIZATION. BEFORE THAT HAPPENS...HOWEVER...RELATED

ISALLOBARIC FORCING AND BACKING OF LOW-LEVEL FLOW TO ITS E SHOULD

AFFECT NRN FRINGE OF AT LEAST MRGLLY UNSTABLE AIR DURING

DAY...BENEATH 50-65 KT LLJ. THIS WOULD ENLARGE LOW-LEVEL HODOGRAPHS

FAVORABLY FOR SUPERCELL/TORNADO POTENTIAL WITH ANY

DISCRETE/SUSTAINED CELLS THAT CAN FORM AHEAD OF MAIN LINE...AND QLCS

TORNADO THREAT WHERE SQUALL LINE ENCOUNTERS UNSTABLE AND SFC-BASED

EFFECTIVE INFLOW PARCELS.

BUOYANCY WILL DIMINISH WITH NWD EXTENT AMIDST WEAK MIDLEVEL LAPSE

RATES. FCST SOUNDINGS SUGGEST MLCAPE RANGING FROM AROUND 1000 J/KG

OVER ATLC COASTAL DELMARVA TO LESS THAN 100 J/KG OVER ERN NY.

STILL...NEAR-NEUTRAL TO VERY SLIGHTLY UNSTABLE THERMODYNAMIC

PROFILES MAY BE SUFFICIENT TO SUPPORT CONDITIONAL WIND POTENTIAL

OVER PARTS OF ERN NY AND WRN NEW ENGLAND...GIVEN STRENGTH OF

AMBIENT/DEEP-LAYER FLOW.

[phlwx]

wouldn't be surprised to see a bump to moderate for some spots in the 30% zone with a 75kt 850 jet being modeled on the GFS. NAM is at 65 kts.

Very impressive wind energy with this storm system.

[ChescoWx]

Wxsim pumps out 1.49" of rain for NW Chesco with this system. Still way below normal YTD rainfall in these parts

[JCT777]

I can deal with one rainy day in this stretch of beautiful early fall weather...the ground is actually pretty dry right now.

[RobbTC]

We've been hashed with possible upgrade to moderate.

[RobbTC]

NWS briefing package prior to SPC update

http://www.erh.noaa.gov/phi/briefing/packages/current_briefing.pdf

[RobbTC]

^{FYI... Midnight on Tuesday night is Midnight on Wednesday morning, otherwise it expires before it starts.}

^{URGENT - WEATHER MESSAGE}

^{NATIONAL WEATHER SERVICE MOUNT HOLLY NJ}

^{254 PM EDT MON SEP 17 2012}

^{...STRONG GUSTY WINDS ARE EXPECTED FROM TUESDAY AFTERNOON INTO}

^{TUESDAY NIGHT...}

^{.A COLD FRONT FROM THE WEST IS FORECAST TO PASS THROUGH EASTERN}

^{PENNSYLVANIA, NORTHEASTERN MARYLAND, DELAWARE AND NEW JERSEY ON}

^{TUESDAY NIGHT. A STRONG SOUTH TO SOUTHWEST WIND IS ANTICIPATED IN}

^{ADVANCE OF THE FRONT'S ARRIVAL.}

^{DEZ001>004-MDZ008-012-015-019-020-NJZ001-007>010-012>027-PAZ054-}

^{055-060>062-067>071-181000-}

^{/O.NEW.KPHI.WI.Y.0009.120918T1600Z-120919T0400Z/}

^{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-}

^{INCLUDING THE CITIES OF...WILMINGTON...DOVER...GEORGETOWN...}

^{REHOBOTH BEACH...ELKTON...CHESTERTOWN...CENTREVILLE...EASTON...}

^{DENTON...NEWTON...WASHINGTON...MORRISTOWN...FLEMINGTON...}

^{SOMERVILLE...NEW BRUNSWICK...FREEHOLD...SANDY HOOK...TRENTON...}

^{PENNSVILLE...GLASSBORO...CAMDEN...CHERRY HILL...MOORESTOWN...}

^{MOUNT HOLLY...JACKSON...MILLVILLE...HAMMONTON...}

^{CAPE MAY COURT HOUSE...OCEAN CITY...ATLANTIC CITY...}

^{LONG BEACH ISLAND...WHARTON STATE FOREST...JIM THORPE...}

^{STROUDSBURG...READING...ALLENTOWN...BETHLEHEM...WEST CHESTER...}

^{NORRISTOWN...DOYLESTOWN...MEDIA...PHILADELPHIA}

^{254 PM EDT MON SEP 17 2012}

^{...WIND ADVISORY IN EFFECT FROM NOON TUESDAY TO MIDNIGHT EDT}

^{TUESDAY NIGHT...}

^{THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY HAS ISSUED A WIND}

^{ADVISORY. IT IS IN EFFECT FROM NOON TUESDAY UNTIL MIDNIGHT TUESDAY}

^NIGHT.

^{* WINDS...A SOUTH WIND AT 20 TO 25 MPH ON TUESDAY AFTERNOON}

^{BECOMING SOUTHWEST ON TUESDAY EVENING. WIND GUSTS AROUND 45 MPH}

^{ARE EXPECTED. GUSTS AROUND 50 MPH ARE POSSIBLE NEAR THE COAST.}

^{* TIMING...WIND SPEEDS ARE FORECAST TO INCREASE ON TUESDAY}

^{AFTERNOON WITH THE STRONG WIND EXPECTED TO CONTINUE ON TUESDAY}

^{EVENING. WIND SPEEDS ARE ANTICIPATED TO DIMINISH LATE ON TUESDAY}

^{NIGHT, FOLLOWING THE PASSAGE OF A COLD FRONT.}

^{* IMPACTS...THE STRONG WIND MAY BRING DOWN TREE LIMBS AND UTILITY}

^{LINES. OUTDOOR ITEMS SUCH AS PATIO FURNITURE AND GARBAGE CANS}

^{WILL BE BLOWN ABOUT. THE WIND MAY ALSO MAKE DRIVING DIFFICULT,}

^{ESPECIALLY ON BRIDGES AND ON ELEVATED ROADWAYS.}

^{PRECAUTIONARY/PREPAREDNESS ACTIONS...}

^{USE EXTRA CAUTION WHEN DRIVING, ESPECIALLY IF YOU ARE OPERATING A}

^{HIGH PROFILE VEHICLE. LIGHT-WEIGHT OUTDOOR OBJECTS SUCH AS PATIO}

^{FURNITURE AND GARBAGE CANS SHOULD BE SECURED.}

[phlwx]

850 jet FTW

[phlwx]

BTW, the high res NAM is showing some 75 kt 850 winds into Central PA in isolated pockets, with some 60 kt winds into Philly.

[NaoPos]

^^^ that's just insane for sept

[tombo82685]

the 18z nam has 50-60 kts 925mb winds over the region, impressive.

[NaoPos]

So NAM does manage to get us aoa 750-900j of cape tomorrow. Not great, but coupled with the wind field and low level moisture (des into the low 70's) there's def a wind threat/isolated tornado threat OUT AHEAD OF THE MAIN EMBEDDED SQUALL LINE.. Any clearing will only enhance the threat.

[MGorse]

^{FYI... Midnight on Tuesday night is Midnight on Wednesday morning, otherwise it expires before it starts.}

The night time period is defined as 6 PM to 6 AM, so technically it is still the Tuesday night time frame (but I see what you are getting at ).

[Quakertown needs snow]

in coming

[wederwarrior]

[Jim Martin]

Trenton, NJ at 5pm tomorrow...

Philadelphia, PA sounding at 5pm tomorrow...

To me, both these soundings are alarming, to say the least.

[dssbss]

For the uneducated what do they say?

[tombo82685]

For the uneducated what do they say?

Its showing a lot of potential spin the stmosphere. The parameters are pretty good for svr weather, except for instability. If some places can pop some sun could be interesting.

[NaoPos]

Its showing a lot of potential spin the stmosphere. The parameters are pretty good for svr weather, except for instability. If some places can pop some sun could be interesting.

Tom, the sounding above shows about 1000j of cape. IMO, that should more than suffice for low topped super cells to develop with the aforementioned shear profiles.

[tombo82685]

Tom, the sounding above shows about 1000j of cape. IMO, that should more than suffice for low topped super cells to develop with the aforementioned shear profiles.

im still not sold on anything besides wind. Its hard as heck to get super cells here during summer time, yet alone mid spetember. I think the clouds and presence of showers/rain in the region will cap the nado threat. But we shall see.

[famartin]

im still not sold on anything besides wind. Its hard as heck to get super cells here during summer time, yet alone mid spetember. I think the clouds and presence of showers/rain in the region will cap the nado threat. But we shall see.

That's what they said in NYC two weekend's ago.

This could produce tor's from both any discrete cells ahead of the main line, or even something embedded within the line itself, a la late September 2003.

[tombo82685]

That's what they said in NYC two weekend's ago.

This could produce tor's from both any discrete cells ahead of the main line, or even something embedded within the line itself, a la late September 2003.

we will see, i definitely can see it with the rather robust shear and helicity. I just think lack of instability and clouds/rain around will hold the nado threat down. the main issue IMHO is with the squall line with wind.

[famartin]

we will see, i definitely can see it with the rather robust shear and helicity. I just think lack of instability and clouds/rain around will hold the nado threat down. the main issue IMHO is with the squall line with wind.

Well, I know everyone gets excited more by tornadoes than by straight-line wind... but this could end up being fairly widespread. Gusts into the 50 mph range can knock branches over, even weakened trees. It doesn't have to be "severe" to cause damage.