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August 2012 Severe Thunderstorm/Convection Discussion


earthlight

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Video taken of the hailer from the severe storm which passed through central Queens around 4pm today. I was in Maspeth, with quarter sized hail (although, I would estimate some larger stones; car alarms went off rampantly around the neighborhood). Winds were very impressive as well, and veered with direction as the storm passed through. Pardon the language used in this video… sheer excitement; I don’t see many hail storms in my neck of the woods. Hailstones at the end of the video.

http://youtu.be/Oc91defA-wQ

That was awesome!!

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BULLETIN - EAS ACTIVATION REQUESTED

FLASH FLOOD WARNING

NATIONAL WEATHER SERVICE NEW YORK NY

545 PM EDT WED AUG 15 2012

THE NATIONAL WEATHER SERVICE IN UPTON NY HAS ISSUED A

* FLASH FLOOD WARNING FOR...

PASSAIC COUNTY IN NORTHEAST NEW JERSEY...

UNION COUNTY IN NORTHEAST NEW JERSEY...

WESTCHESTER COUNTY IN SOUTHEAST NEW YORK...

BERGEN COUNTY IN NORTHEAST NEW JERSEY...

ESSEX COUNTY IN NORTHEAST NEW JERSEY...

HUDSON COUNTY IN NORTHEAST NEW JERSEY...

ROCKLAND COUNTY IN SOUTHEAST NEW YORK...

* UNTIL 745 PM EDT...

* AT 541 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED

AN AREA OF HEAVY THUNDERSTORMS MOVING ACROSS THE WARNING AREA.

RAINFALL RATES OF ONE TO TWO INCHES IN ONE HOUR ARE POSSIBLE.

EXCESSIVE RUNOFF WILL CAUSE FLOODING OF HIGHWAYS...STREETS AND

UNDERPASSES...AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL

CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES

AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE

ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS

SAFELY. MOVE TO HIGHER GROUND.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO

AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY

DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL

ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED

ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

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Sorry I was out all day but I was in Lynbrook and the thunder was so loud I could hear inside the building and then when I went back to the city big flash of lightning followed a huge clap thunder came out of nowhere but overall just some heavy rains from both storms in the city and Lynbrook. Missed the good storms at home because I was busy away.

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SPC only has 5% risk of damaging winds of hail for entire today. While Upton seems to be more concerned for more severe wx, N&W of NYC. I think I agree more with Upton's reasoning. Both latest runs of the SPC WRF and HRRR have line of showers and t-storms coming through this evening.

Upton AFD:

THE BULK OF THE SHOWER AND THUNDERSTORM ACTIVITY WILL HOLD OFF

UNTIL TONIGHT...BUT WILL HAVE TO WATCH IF CONVECTION MATURES INTO

AN ORGANIZED LINE OF THUNDERSTORMS AHEAD OF THE COLD FRONT THIS

AFTERNOON ACROSS CENTRAL NY/PA. THIS TYPE OF LINE WOULD LIKELY

TRACK EAST TOWARDS THE AREA LATE THIS AFTERNOON INTO THIS EVENING.

IT WOULD MOVE INTO AN UNSTABLE ENOUGH AIR MASS ACROSS FAR WESTERN

PORTIONS OF THE AREA TO SUPPORT STRONG TO SEVERE STORMS. FURTHER

EAST...INCLUDING NYC...THE LATER THE TIMING OF AN ORGANIZED

LINE...WANING INSTABILITY AND/OR THE MARINE LAYER SHOULD BEGIN

WEAKENING CONVECTION. THE DAYSHIFT WILL BE ABLE TO MONITOR...AND

ADJUST SEVERE THREAT AS NEEDED.

NORTHERN FAIRFIELD-WESTERN PASSAIC-EASTERN PASSAIC-WESTERN BERGEN-

EASTERN BERGEN-WESTERN ESSEX-EASTERN ESSEX-WESTERN UNION-

EASTERN UNION-ORANGE-PUTNAM-ROCKLAND-NORTHERN WESTCHESTER-

719 AM EDT FRI AUG 17 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN

CONNECTICUT...NORTHEAST NEW JERSEY AND SOUTHEAST NEW YORK.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A CHANCE FOR AN ORGANIZED LINE OF STRONG TO SEVERE

STORMS TO AFFECT THE REGION LATE TODAY INTO THIS EVENING. THE

GREATEST THREAT IS TO THE WEST AND NORTHWEST OF NEW YORK CITY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

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SPC only has 5% risk of damaging winds of hail for entire today. While Upton seems to be more concerned for more severe wx, N&W of NYC. I think I agree more with Upton's reasoning. Both latest runs of the SPC WRF and HRRR have line of showers and t-storms coming through this evening.

Upton AFD:

THE BULK OF THE SHOWER AND THUNDERSTORM ACTIVITY WILL HOLD OFF

UNTIL TONIGHT...BUT WILL HAVE TO WATCH IF CONVECTION MATURES INTO

AN ORGANIZED LINE OF THUNDERSTORMS AHEAD OF THE COLD FRONT THIS

AFTERNOON ACROSS CENTRAL NY/PA. THIS TYPE OF LINE WOULD LIKELY

TRACK EAST TOWARDS THE AREA LATE THIS AFTERNOON INTO THIS EVENING.

IT WOULD MOVE INTO AN UNSTABLE ENOUGH AIR MASS ACROSS FAR WESTERN

PORTIONS OF THE AREA TO SUPPORT STRONG TO SEVERE STORMS. FURTHER

EAST...INCLUDING NYC...THE LATER THE TIMING OF AN ORGANIZED

LINE...WANING INSTABILITY AND/OR THE MARINE LAYER SHOULD BEGIN

WEAKENING CONVECTION. THE DAYSHIFT WILL BE ABLE TO MONITOR...AND

ADJUST SEVERE THREAT AS NEEDED.

NORTHERN FAIRFIELD-WESTERN PASSAIC-EASTERN PASSAIC-WESTERN BERGEN-

EASTERN BERGEN-WESTERN ESSEX-EASTERN ESSEX-WESTERN UNION-

EASTERN UNION-ORANGE-PUTNAM-ROCKLAND-NORTHERN WESTCHESTER-

719 AM EDT FRI AUG 17 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHERN

CONNECTICUT...NORTHEAST NEW JERSEY AND SOUTHEAST NEW YORK.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A CHANCE FOR AN ORGANIZED LINE OF STRONG TO SEVERE

STORMS TO AFFECT THE REGION LATE TODAY INTO THIS EVENING. THE

GREATEST THREAT IS TO THE WEST AND NORTHWEST OF NEW YORK CITY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

There's nothing wrong with SPC's forecast, today/tonight is extremely marginal. Instability is somewhat decent, but everything else is junk.

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There's nothing wrong with SPC's forecast, today/tonight is extremely marginal. Instability is somewhat decent, but everything else is junk.

All the high res models seem to agree best forcing is over the I-87 corridor upstate and from central PA north...the line will probably be solid from W MA into ERN and CNTRL NY through NRN PA all afternoon but whether or not it can maintain itself into NJ and then into the metro area is a big question mark.

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Its amazing, the NAM/GFS and Euro are all putting out about the same amount of precip but the timing is completely different. The NAM has the bulk overnight and out of here by mid morning. The Euro has it linger through early afternoon and the GFS basically says we see nothing until tomorrow and it lasts until evening.

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Its amazing, the NAM/GFS and Euro are all putting out about the same amount of precip but the timing is completely different. The NAM has the bulk overnight and out of here by mid morning. The Euro has it linger through early afternoon and the GFS basically says we see nothing until tomorrow and it lasts until evening.

Each model has a slightly different handling of the weak frontal wave that would focus the convection.

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Its amazing, the NAM/GFS and Euro are all putting out about the same amount of precip but the timing is completely different. The NAM has the bulk overnight and out of here by mid morning. The Euro has it linger through early afternoon and the GFS basically says we see nothing until tomorrow and it lasts until evening.

Euro has a similar start time as the NAM. 2-3 hours later on the euro; around 1am tonight and like you said, lasting until noonish from NYC west and longer into the afternoon for LI.

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Some of the parameters are in place...for example, the Lifted Index is expected to be quite high and we should obviously have good daytime heating.

The big question is the timing of the cold front, which is a bit slower than ideal.

Also, wind shear values are not very impressive at all, although once you get west of the Hudson and into the Catskills, the threat goes up.

I would like to think that the areas NW of NYC are on the SE edge of the severe weather potential. I could see an isolated storm or two bring some strong winds and small hail to northern NJ or the lower/mid-Hudson Valley.

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