Big NYC Storm This Morning

[PhilDernerJr]

Though we all know what they are, what actually constitutes a tornado to them?

[MarkLawrence]

Exactly how tornadoes form is still not completely known. But after many years of study, meteorologists, scientists who study weather, do know some things for sure.

Tornadoes can form as part of several different types of storms but they are produced inside powerful thunderstorms more than any other. Tornadoes form where warm, moist air and cold, dry air meet and begin to create updrafts that develop into massive rotating cumulonimbus clouds or supercells. Sometimes a spinning column of air called a vortex forms within these clouds. When this vortex becomes visible as a funnel cloud and reaches the ground, a tornado is created.

Not all tornadoes form as part of a thunderstorms. Meteorologists have discovered that sometimes a horizontal layer of air can be set spinning. This happens when it gets caught between two other layers of air that are moving in opposite directions. This would be similar to rolling a pencil between your hands. With the help of updrafts and gravity this column can become vertical and extend to the ground to form a tornado.

The word tornado comes from two Spanish words, tronado meaning thunderstorm and tornar meaning to turn .

(c) Jim Cornish - borrowed from his web site.

[USAF Pilot 07]

Though we all know what they are, what actually constitutes a tornado to them?

Cornish's explanation is very well put...

To answer your question about what constitutes a Tornado to the NWS.... A Tornado, to the NWS, and by definition, is a rapidly rotating vortex that extends from the clouds to the ground.

As for how the NWS will determine whether or not a tornado had actually touched down.... The NWS will do a few things to determine whether or not to make the determination that a tornado occurred.

Firstly, they will gather all the damage reports received, and pinpoint them on a map.
Then, they will go back and look at radar images, and especially velocity captures to look for evidence of rotation. Velocity images show motion both towards and away from the radar. Generally, on one side of the radar, you will have motion towards the radar, and on the other side of the radar, motion away from the radar. What the NWS will look for is rotation "couplets" at the location around where the tornado was reported. This is where even though the overall motion will be towards or away from the radar, at a certain area, generally in a confined spot, you have both motion towards AND away from the radar. This is indicative of rotation, because in order for you to have horizontal motion both towards and away from the radar in basically the same spot, you have to have some sort of spinning. The stronger the rotation, the more likely a tornado is present or could form. The NWS will look at different angles too (i.e. different altitudes) to see where rotation was really present - i.e. whether just at lower levels, or throughout the atmosphere...
Also, if you've ever heard a Tornado Warning, most go like this: "at XXXX local time, National Weather Service Doppler Radar indicated a Tornado at XXX". These warnings mean that even though no one has reported an actual Tornado, there is significant evidence from looking at the radar (both reflectivity and velocity) to let people know that a Tornado either is, or could very shortly form. In the 1980s, before Doppler Radar was introduced, Tornado Warnings were only issued when there was an actual no-**** Tornado on the ground. This left people will little lead time, because a Tornado was generally only reported when it was close to, or on top off a populated area. Since radar was introduced, we've been able to really give people a heads up on what is coming, and what could very well materialize, and give them plenty of time to seek shelter.

But back to the subject at hand... After reviewing radar captures and some other data, the NWS will generally send out a trained field team to the location to assess damage and talk to witnesses. Generally, what they are looking for is evidence that a tornado - i.e. a rapidly rotating vortex - had indeed touched down and that the damage wasn't just caused by strong winds. What they will look at is how stuff was destroyed. For example, they will look at how trees were snapped, what kind of shape objects were left in, what kind of stuff was destroyed and what kind of stuff wasn't destroyed. Sometimes, they will fly over the area in question to see what kind of damage pattern was left. Many times it will be easy to see the vortex signature from the air, especially in less urban areas.

After all this, they will come to a conclusion on whether or not a tornado did indeed touch down, and if it did what strength they estimated the tornado to be.

Sorry if the explanation was a little confusing. It's hard to explain some stuff without images, and it is like 245AM so I am kinda tired...

[Matt Molnar]

PUBLIC INFORMATION STATEMENT...REVISED
TORNADO DAMAGE SURVEY
NATIONAL WEATHER SERVICE UPTON NY
232 PM EDT TUE AUG 14 2007

...NEW YORK CITY TORNADO ON AUGUST 8TH...

NATIONAL WEATHER SERVICE METEOROLOGISTS ALONG WITH NEW YORK CITY
EMERGENCY MANAGEMENT OFFICIALS CONFIRMED THAT SEVERAL TORNADO
TOUCHDOWNS OCCURRED ALONG AN APPROXIMATE 9 MILE PATH FROM STATEN
ISLAND TO BROOKLYN IN THE EARLY MORNING OF AUGUST 8TH.

THE FIRST TORNADO TOUCHDOWN WAS IN STATEN ISLAND AT APPROXIMATELY
6:22 AM IN THE VICINITY OF ST. AUSTINS PLACE IN THE LIVINGSTON -
RANDALL MANOR AREA. THE TORNADO MOVED EAST...WITH ADDITIONAL DAMAGE
OCCURRING IN THE TOMPKINSVILLE AREA. MOST OF THE DAMAGE IN STATEN
ISLAND WAS TO TREES...AND ESTIMATED AT EF-1 ON THE ENHANCED FUJITA
SCALE...WITH WINDS OF 86 TO 100 MPH.

BASED ON RE-ANALYSIS OF RADAR DATA, THE STATEN ISLAND TORNADO
APPARENTLY DISSIPATED AS A SECOND CIRCULATION DEVELOPED JUST NORTH
OF THE FIRST CIRCULATION. THE DAMAGE IN TOMPKINSVILLE MAY BE A
RESULT OF THIS SECOND CIRCULATION.

THIS CIRCULATION INTENSIFIED AS IT MOVED EAST ACROSS THE VERRAZANO
NARROWS. THE TORNADO RE-DEVELOPED BY THE TIME THE CIRCULATION MOVED
ON SHORE IN BROOKLYN. DAMAGE IN THE FORM OF FALLEN TREES AND
STRUCTURAL ROOF DAMAGE OCCURRED IN BAY RIDGE STARTING IN THE AREA
FROM SHORE ROAD BETWEEN 71ST AND 78TH EASTWARD TO BAY RIDGE BLVD.
THIS OCCURRED AT APPROXIMATELY 6:32 AM. THE TORNADO MAY HAVE BRIEFLY
LIFTED AND THEN TOUCHED DOWN AGAIN ON BAY RIDGE AVENUE BETWEEN THIRD
AND FOURTH AVENUES...AND CONTINUED ON AN EAST-NORTHEAST PATH ACROSS
68TH STREET BETWEEN THIRD AND FOURTH AVENUES. ELEVEN HOMES IN THIS
SECTION HAD MODERATE TO SEVERE ROOF DAMAGE. THE STORM CONTINUED TO
MOVE EAST-NORTHEAST INTO LEIF ERICSON PARK SQUARE...WHERE SEVERE
DAMAGE TO TREES OCCURRED. AS THE TORNADO LIFTED...IT TORE OFF THE
ROOF OF THE NISSAN CAR DEALERSHIP AT THE CORNER OF 66TH STREET AND
FIFTH AVENUE. THE TORNADO RETURNED TO THE GROUND FARTHER
NORTHEAST...WITH SCATTERED TREE DAMAGE ALONG 6TH AVENUE. BASED ON
THE ASSESSED DAMAGE IN BAY RIDGE...THIS TORNADIC DAMAGE IS
CLASSIFIED AS EF-2 WITH ESTIMATED WIND SPEEDS OF 111 TO 135 MPH.

THE TORNADO RETURNED TO THE GROUND AS ANOTHER POCKET OF SIGNIFICANT
DAMAGE OCCURRED ON 58TH STREET BETWEEN FIFTH AND SIXTH AVENUES. THE
ROOF WAS RIPPED OFF OF 5 HOMES...AND TREE DAMAGE INDICATES STRONG
EF-1 DAMAGE.

THE TORNADO THEN HEADED EAST...AND TOUCHED DOWN AT LEAST THE FOURTH
BUT FINAL TIME IN KENSINGTON JUST EAST OF THE INTERSECTION OF CHURCH
AVENUE AND BEVERLY ROAD AT APPROXIMATELY 6:40 AM. NUMEROUS
TREES...APPROXIMATELY 30...WERE UPROOTED ALONG OCEAN PARKWAY AS THE
TORNADO MOVED EAST. THE TORNADO PRODUCED SIGNIFICANT DAMAGE TO TREES
AND STRUCTURES IN THE AREA WITH EAST 8TH AND 7TH STREETS BEING HIT
HARD. DAMAGE WAS REPORTED AS FAR EAST AS ARGYLE ROAD. THE TORNADO
WAS ON THE GROUND FOR APPROXIMATELY 1/2 MILE IN THIS AREA BEFORE IT
LIFTED.

NATIONAL WEATHER SERVICE METEOROLOGISTS ALONG WITH METEOROLOGISTS
FROM THE STATE UNIVERSITY OF NEW YORK AT STONY BROOK CONTINUE TO
ANALYZE DATA FROM THIS HISTORIC METEOROLOGICAL EVENT.

THE NATIONAL WEATHER SERVICE HAD ISSUED A TORNADO WARNING FOR
PORTIONS OF STATEN ISLAND AND BROOKLYN AT 6:28 AM. A SECOND TORNADO
WARNING WAS ISSUED AT 6:50 AM FOR SECTIONS OF
BROOKLYN...QUEENS...AND NASSAU COUNTY.

$$

TONGUE/CRISTANTELLO

[Mellyrose]

We're in Kansas, Toto? :shock: