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2013 Mt. Holly CWA Convection Thread


SouthernNJ

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sounds modest but encouraging

 DISCUSSION...S CNTRL PA SQLN EXPECTED TO CONTINUE GENERALLY ESE AT
   40 KTS INTO THE UPR CHESAPEAKE BAY REGION AND LWR DELAWARE VLY
   THROUGH MID-EVE. THE WRN END OF THE CONVECTIVE SYSTEM
   COULD...HOWEVER...TAKE A BIT MORE OF A RIGHTWARD /SSE/ TURN IN THE
   NEXT HOUR OR TWO AS IT FURTHER CRESTS THE BLUE RIDGE MTNS. AREA VWP
   DATA...COUPLED WITH THE 00Z IAD RAOB THERMODYNAMIC PROFILE...SUGGEST
   ENVIRONMENT WILL REMAIN FAVORABLE FOR ADDITIONAL FORWARD-PROPAGATING
   LINE SEGMENTS WITH A POTENTIAL FOR DMGG WIND...DESPITE ONSET OF
   NIGHTFALL.

   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.
   A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION
   VECTOR 30030.


   ...CORFIDI

Corfidi is supposed to be one of the better ones too (according to one of my profs)

 

By "mean storm vector" he actually means 'Corfidi vector". At least that's how I learned it. :) I'm suprised that line made it over the mountains tho.

 

Its the name at the end of the discussion.  The guy who invented the Corfidi vector is still a forecaster at SPC, and he's working tonight.

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15% odds on wind/hail along and nw of 295 for today.

 

FYI, we went from a Thursday slight risk for Eastern PA in the day 3 outlook yesterday to a "see text" in the day 2 today. Wouldn't shock me to see it get bumped back up to slight tomorrow.

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15% odds on wind/hail along and nw of 295 for today.

 

FYI, we went from a Thursday slight risk for Eastern PA in the day 3 outlook yesterday to a "see text" in the day 2 today. Wouldn't shock me to see it get bumped back up to slight tomorrow.

 

You are some wizard....Slight risk again for tomorrow.

 

Also:

 

 

mcd1245.gif

   MESOSCALE DISCUSSION 1245   NWS STORM PREDICTION CENTER NORMAN OK   1219 PM CDT WED JUN 26 2013   AREAS AFFECTED...PORTIONS OF SERN PA...FAR ERN WV...CENTRAL/ERN   MD...DE...THE DISTRICT OF COLUMBIA...A LARGE PART OF VA   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE    VALID 261719Z - 261945Z   PROBABILITY OF WATCH ISSUANCE...40 PERCENT   SUMMARY...THE AREA IS BEING MONITORED FOR AN INCREASING POTENTIAL   FOR SVR THUNDERSTORMS THIS AFTERNOON...AND THE ISSUANCE OF A SVR   TSTM WATCH IS POSSIBLE.   DISCUSSION...RECENT 7- AND 9-KM RADAR CAPPI DATA INDICATE AN UPTICK   IN DEEP CONVECTION ALONG A WEAKLY ORGANIZED OUTFLOW   BOUNDARY/DIFFERENTIAL HEATING ZONE ARCING ALONG THE WV/VA BORDER   INTO FAR SWRN VA. ADDITIONAL CONVECTION WILL LIKELY DEVELOP INVOF   THIS BOUNDARY...AIDED BY DIURNALLY DEEPENING OROGRAPHIC CIRCULATIONS   INVOF THE CNTRL APPALACHIANS. THE AIR MASS E OF THE BLUE RIDGE   MOUNTAINS IS STRONGLY DESTABILIZING TO THE S OF A MORE W/E-ORIENTED   DIFFERENTIAL HEATING ZONE ACROSS S-CENTRAL/SERN PA.    DIABATIC SFC HEATING SUPPORTING TEMPERATURES IN THE MIDDLE/UPPER 80S   TO AROUND 90 DEGREES AMIDST SFC DEWPOINTS IN THE MIDDLE 60S TO   AROUND 70F IS SUPPORTING MLCAPE ON THE ORDER OF 1500-3000 J/KG PER   MODIFIED 12Z RAOBS. WITH VIS SATELLITE IMAGERY INDICATING   PARTLY/MOSTLY SUNNY SKIES AWAY FROM ONGOING CONVECTION...FURTHER   DESTABILIZATION IS ANTICIPATED THROUGH THE AFTERNOON. THIS WILL   SUPPORT VIGOROUS UPDRAFTS/DOWNDRAFTS...WITH SVR WIND AND HAIL   POTENTIAL INCREASING THROUGH THE AFTERNOON AS CONVECTION MOVES OVER   THE PIEDMONT AND TOWARD THE COASTAL PLAIN. DCAPE VALUES INCREASING   OVER 1000 J/KG AND ENHANCED WATER-LOADING PROCESSES ASSOCIATED WITH   PW VALUES OF 1.50-1.75 INCHES PER GPS DATA WILL ENHANCE THE DMGG   WIND POTENTIAL.   MID-LEVEL FLOW IS ONLY MODEST PER LWX/FCX VWP DATA -- ON THE ORDER   OF 20 KT FROM THE W -- WHICH MAY ONLY CONTRIBUTE TO MARGINALLY   ORGANIZED...EWD-MOVING MULTICELL STORM CLUSTERS. SOME INCREASE IN   MID-LEVEL FLOW/EFFECTIVE BULK SHEAR MAY OCCUR LATER TODAY AS A   CONVECTIVELY AUGMENTED MID-LEVEL PERTURBATION CURRENTLY OVER OHIO   PER MOISTURE CHANNEL IMAGERY APPROACHES. HOWEVER...THIS MAY NOT   OCCUR UNTIL AFTER MORE SUBSTANTIAL CONVECTIVE OVERTURNING OCCURS   WITHIN THE ONGOING WARM SECTOR. THIS BREEDS UNCERTAINTY REGARDING   THE OVERALL ORGANIZATION OF CONVECTION AND CORRESPONDING COVERAGE OF   SVR TSTMS...THOUGH THE AREA WILL BE MONITORED FOR POSSIBLE WW   ISSUANCE THROUGH THE AFTERNOON.   ..COHEN/KERR.. 06/26/2013
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URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 373
   NWS STORM PREDICTION CENTER NORMAN OK
   255 PM EDT WED JUN 26 2013

   THE NWS STORM PREDICTION CENTER HAS ISSUED A

   * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
     DISTRICT OF COLUMBIA
     DELAWARE
     CENTRAL AND EASTERN MARYLAND
     SOUTHERN NEW JERSEY
     SOUTHEASTERN PENNSYLVANIA
     CENTRAL AND EASTERN VIRGINIA
     COASTAL WATERS

   * EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 255 PM
     UNTIL 1000 PM EDT.

   * PRIMARY THREATS INCLUDE...
     SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
     SEVERAL LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE

   THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95
   STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES NORTH OF
   ATLANTIC CITY NEW JERSEY TO 45 MILES WEST OF SOUTH HILL VIRGINIA.
    FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
   OUTLINE UPDATE (WOUS64 KWNS WOU3).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
   FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
   DO PRODUCE TORNADOES.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 372...

   DISCUSSION...SCATTERED STRONG/SEVERE STORM DEVELOPMENT IS NOW WELL
   UNDERWAY ALONG THE BLUE RIDGE INTO THE VICINITY OF THE LEE SURFACE
   TROUGH ACROSS THE MID ATLANTIC STATES.  GIVEN MODERATELY LARGE CAPE
   ACTIVITY IS EXPECTED TO CONTINUE TO INCREASE IN COVERAGE AND DEVELOP
   EASTWARD TOWARD COASTAL AREAS...AIDED BY FORCING ASSOCIATED WITH AN
   IMPULSE PROGRESSING ACROSS THE CENTRAL APPALACHIANS.  UPSCALE GROWTH
   INTO A LOOSELY ORGANIZED LARGER CLUSTER OF STORMS IS NOT OUT OF THE
   QUESTION...PERHAPS ENHANCED...ACROSS PARTS OF MARYLAND AND THE
   DELMARVA PENINSULA INTO NORTHERN MID ATLANTIC COASTAL AREAS...BY A
   LINGERING BELT OF MODEST MID-LEVEL FLOW.

   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
   MOTION VECTOR 27030.


   ...KERR
 

ww0373_overview_wou.gif Hazard
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Numbers look really good focused on Philly right now. Lets see what happens with the cell just north of Lancaster.

 

Some wind, heavy rain and a few rumbles/cg strikes. The heaviest stuff passed directly over me. Max rain rate was 4.32" IMBY, KLNS recorded a gust to 29. Not a great storm, but a decent one.

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You are some wizard....Slight risk again for tomorrow.

 

more a product of spc inconsistency within the forecasters. the track record of these shifts within the day is getting rather lengthy.

 

it's one thing to upgrade from slight to mod or to extend a risk farther east because a MCS is overperforming, it's another to simply go from <5% to a slight in one outlook.  

 

i don't like to beat up on them but the last couple of years have seen them do risk upgrades within the day much more frequently than they really should or used to.

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You are some wizard....Slight risk again for tomorrow.

more a product of spc inconsistency within the forecasters. the track record of these shifts within the day is getting rather lengthy.

it's one thing to upgrade from slight to mod or to extend a risk farther east because a MCS is overperforming, it's another to simply go from <5% to a slight in one outlook.

i don't like to beat up on them but the last couple of years have seen them do risk upgrades within the day much more frequently than they really should or used to.

Yeah I hear you

Also there is some impressive lightning with this cell moving through northern delco

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