Jump to content
  • Member Statistics

    17,604
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

Severe weather potential friday 7/29


earthlight

Recommended Posts

Also a 5% tornado risk area directly over NJ/EPA/NYC/SE NY

day1probotlk_1630_torn.gif

..OH VALLEY TO MID ATLANTIC COAST

EWD PROGRESSION OF WELL-DEFINED VORTICITY MAXIMUM OVER LAKE ONTARIO

AND LARGER-SCALE SHORT WAVE TROUGH OVER ONTARIO WILL CONTRIBUTE TO A

CORRIDOR OF HEIGHT FALLS FROM THE LOWER GREAT LAKES INTO NEW ENGLAND

DURING THE D1 PERIOD. IN THE LOW LEVELS...SURFACE LOW NEAR TORONTO

WILL DEVELOP ENEWD...REACHING THE ADIRONDACKS BY EVENING WHILE

TRAILING COLD FRONT ADVANCES SEWD THROUGH THE LOWER GREAT LAKES.

LATE MORNING VISIBLE SATELLITE IMAGERY AND RADAR DATA INDICATE

GRADUALLY DEEPENING CONVECTION OVER PORTIONS OF WRN NY ALONG THE SRN

FRINGE OF ABOVE-MENTIONED VORTICITY MAXIMUM WHERE TEMPERATURES HAVE

WARMED TO AROUND 80 F. EXPECT A FURTHER INCREASE IN STORM COVERAGE

AND INTENSITY TODAY ALONG THE SRN FRINGE OF DENSER...MORE PERSISTENT

CLOUDS /I.E. SRN NY INTO PA/ WHERE LOCALLY STRONG DIABATIC WARMING

AND BOUNDARY LAYER DEWPOINTS IN THE 70S WILL BOOST MLCAPE TO

1500-2500 J/KG. MOREOVER...THIS CORRIDOR WILL RESIDE ALONG SRN

FRINGE OF 40-50 KT WLY MIDLEVEL WIND MAXIMUM ATTENDANT TO THE LAKE

ONTARIO VORTICITY MAXIMUM...RESULTING IN SUFFICIENT DEEP-LAYER SHEAR

FOR ORGANIZED STORM MODES...INCLUDING SUPERCELLS AND BOWING

STRUCTURES. WHILE DAMAGING WINDS WILL BE THE PRIMARY HAZARD...A

TORNADO OR TWO WILL BE POSSIBLE OVER THE DE AND LOWER HUDSON VALLEYS

THIS AFTERNOON WHERE LOW-LEVEL SHEAR IS ENHANCED ALONG RETREATING

WARM FRONT.

Link to comment
Share on other sites

  • Replies 283
  • Created
  • Last Reply

Meso. disc. out

MESOSCALE DISCUSSION 1781

NWS STORM PREDICTION CENTER NORMAN OK

1157 AM CDT FRI JUL 29 2011

AREAS AFFECTED...PORTIONS PA...NJ...NY.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 291657Z - 291900Z

SVR POTENTIAL FCST TO INCREASE THROUGH NEXT 2-3 HOURS ACROSS THIS

REGION AS AIR MASS DESTABILIZES...BOTH IN BOUNDARY LAYER AND ALOFT.

DAMAGING GUSTS ARE MAIN CONCERN...WITH CONDITIONAL TORNADO

POTENTIAL.

MCV IS EVIDENT IN COMPOSITE REFLECTIVITY LOOPS OVER ERN LAKE ONT AND

ADJOINING SERN ONT...AND SHOULD MOVE EWD TO EXTREME NRN NY THROUGH

LATE AFTERNOON. STRENGTHENING MID-UPPER LEVEL WINDS ARE EVIDENT IN

AVAILABLE VWP SAMPLING...CONSISTENT WITH TIGHTENING HEIGHT GRADIENTS

BOTH S OF MCV AND IN ADVANCE OF APCHG SHORTWAVE TROUGH. THIS IS

INCREASING DEEP-LAYER SHEAR ACROSS CENTRAL/NRN PA AND ADJOINING

PORTIONS NY. EFFECTIVE SHEAR MAGNITUDES 40-50 KT SHOULD BE COMMON

ACROSS THIS AREA BY 19Z...AS TSTMS DEVELOP AND INCREASE IN COVERAGE.

BUOYANCY SHOULD CONTINUE TO INCREASE...ESPECIALLY IN AREAS OF CLOUD

BREAKS ACROSS PORTIONS SRN NY AND NRN PA EVIDENT IN VIS IMAGERY.

INSOLATION AND SFC DEW POINTS 70S F WILL OFFSET WEAK LAPSE RATES

ALOFT ENOUGH TO SUPPORT WARM-SECTOR MLCAPE RANGING FROM AROUND 1500

J/KG OVER PORTIONS CENTRAL/SRN NY TO 2500 J/KG OVER SOME OF

CENTRAL-ERN PA.

SFC MESOANALYSIS SHOWS WARM FRONT FROM S-CENTRAL NJ NWWD ACROSS ERN

PA...BECOMING ILL-DEFINED AMIDST COOLING EFFECTS OF EARLIER

CLOUDS/PRECIP OVER CENTRAL NY JUST N PA BORDER. COMBINED WARM FRONT

AND DIFFERENTIAL-HEATING BOUNDARY SHOULD MOVE NEWD ACROSS SRN NY AND

NERN PA THROUGH AFTERNOON...SPREADING FAVORABLY DESTABILIZING AIR

MASS NEWD. LOW-LEVEL SHEAR WILL BE MAXIMIZED INVOF THAT BOUNDARY

WHERE BACKING OF SFC WINDS AND ENHANCED BOUNDARY-LAYER VORTICITY

WILL BE PRESENT...SUPPORTING SUPERCELL POTENTIAL WITH ANY RELATIVELY

SUSTAINED/DISCRETE TSTMS. OTHERWISE...DEEP-LAYER KINEMATIC PROFILE

FAVORS DAMAGING GUSTS...WHETHER IN ISOLATED FORM FROM DISCRETE CELLS

OR BETTER-ORGANIZED WIND POTENTIAL FROM BOW ECHOES.

..EDWARDS.. 07/29/2011

Link to comment
Share on other sites

Here is the link to the model. For those who don't know...this model has predicted exact locations of thunderstorms 24 hours in advance at a consistency which I have never seen. It has it's flaws...and you have to know how to use it...but it is a jewel amongst otherwise flawed mesoscale and convective prediction model schemes.

http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/

Link to comment
Share on other sites

Here is the link to the model. For those who don't know...this model has predicted exact locations of thunderstorms 24 hours in advance at a consistency which I have never seen. It has it's flaws...and you have to know how to use it...but it is a jewel amongst otherwise flawed mesoscale and convective prediction model schemes.

http://www.emc.ncep....nt4km/conus/12/

refd_1000m_f11.gif

Link to comment
Share on other sites

Here is the link to the model. For those who don't know...this model has predicted exact locations of thunderstorms 24 hours in advance at a consistency which I have never seen. It has it's flaws...and you have to know how to use it...but it is a jewel amongst otherwise flawed mesoscale and convective prediction model schemes.

http://www.emc.ncep....nt4km/conus/12/

55msfd.jpg

Link to comment
Share on other sites

NVA is doing its job with clearing out some cloud debris. The wind shear coming in with the s/w is pretty freagin good, probably the best speed shear of the year. All the other events were lacking under h7. The differential heating boundary is going to focus either a supercell or a bow-head structure capable of rotation. Given how this year has gone, it will probably be NE PA into NW NJ. A 10 degree drop in temperature currently exists from NE NJ to SW CT, so perhaps NYC is in this threat too.

Link to comment
Share on other sites

NVA is doing its job with clearing out some cloud debris. The wind shear coming in with the s/w is pretty freagin good, probably the best speed shear of the year. All the other events were lacking under h7. The differential heating boundary is going to focus either a supercell or a bow-head structure capable of rotation. Given how this year has gone, it will probably be NE PA into NW NJ. A 10 degree drop in temperature currently exists from NE NJ to SW CT, so perhaps NYC is in this threat too.

There was a few good storms in Pike County, Pa. this year, they could be the winners again later on.

Link to comment
Share on other sites

NVA is doing its job with clearing out some cloud debris. The wind shear coming in with the s/w is pretty freagin good, probably the best speed shear of the year. All the other events were lacking under h7. The differential heating boundary is going to focus either a supercell or a bow-head structure capable of rotation. Given how this year has gone, it will probably be NE PA into NW NJ. A 10 degree drop in temperature currently exists from NE NJ to SW CT, so perhaps NYC is in this threat too.

Interesting timing with the warm front/differential heating boundary moving northward throughout the day today. I agree with the potential rotation along that boundary given the low level shear and backing wind profiles evident on soundings from the past few NAM runs.

Right now it's a waiting game. The shortwave/vorticity was not modeled to reach north/central PA until 18z. So within the next hour or so we should see some development there. Then the kinematic support and southeastward motion can work it's magic.

Link to comment
Share on other sites

There was a few good storms in Pike County, Pa. this year, they could be the winners again later on.

I agree that NE PA has been the spot this year (again). This line will rapidly fire in the deep theta-e ridge across E-C PA and ultimately the Delaware Valley 4-8pm. I think the northern edge will be occasionally tornadic...I just don't know where that will be right now.

We all agree that discrete supercells out ahead of the line is looking a bit unlikely and this will like be a QLCS (I hate this term) with occasional spin?

Link to comment
Share on other sites

This is all really curiously well timed to the be honest---you can see the shortwave and vorticity now over North Central PA on mesoscale analysis, and it's juxtaposed with 50+kts of 0-6km bulk shear. The 0-3km helicity is also well increased in that area..up over 100 m2/s2 over the last hour.

That one updraft just north of the PA border west of BGM is just barely straddling north of the impressive numbers..currently sitting in 45kts of effective bulk shear and 200 m2/s2 of 0-3km helicity. Surface based instability increases dramatically to it's southwest..so we will see if that's the tipping point for development.

Otherwise back to the west-southwest of that feature..it looks like we're close to kickoff given the latest visible scan.

http://climate.cod.edu/data/satellite/1km/LongIsland/current/LongIsland.vis.gif

Link to comment
Share on other sites

Interesting timing with the warm front/differential heating boundary moving northward throughout the day today. I agree with the potential rotation along that boundary given the low level shear and backing wind profiles evident on soundings from the past few NAM runs.

Right now it's a waiting game. The shortwave/vorticity was not modeled to reach north/central PA until 18z. So within the next hour or so we should see some development there. Then the kinematic support and southeastward motion can work it's magic.

The vort max is currently over W NY, lobing down into NW PA. It should be intersecting the MLCAPE axis in another hour. That is when our wonderful mesos do initiate the convection (19z).

Link to comment
Share on other sites

This is all really curiously well timed to the be honest---you can see the shortwave and vorticity now over North Central PA on mesoscale analysis, and it's juxtaposed with 50+kts of 0-6km bulk shear. The 0-3km helicity is also well increased in that area..up over 100 m2/s2 over the last hour.

That one updraft just north of the PA border west of BGM is just barely straddling north of the impressive numbers..currently sitting in 45kts of effective bulk shear and 200 m2/s2 of 0-3km helicity. Surface based instability increases dramatically to it's southwest..so we will see if that's the tipping point for development.

Otherwise back to the west-southwest of that feature..it looks like we're close to kickoff given the latest visible scan.

http://climate.cod.e...gIsland.vis.gif

Sorry, didn't see this. Looks like we agree! Game on...:scooter:

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...