Gert brushing Bermuda; a new all-time 1-day rainfall record for NYC

By: Dr. Jeff Masters , 2:30 PM GMT on August 15, 2011

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Tropical Storm Gert, the 7th named storm of the Atlantic hurricane season, is here. Gert's formation on August 14 marks the 4th earliest date for the season's 7th storm. Only 2005, 1995, and 1936 have had an earlier formation of the season's 7th storm. Gert will pass very close to Bermuda today, but thus far the island has had no wind or rain from Gert, with top winds at the Bermuda Airport of just 9 mph as of 10 am EDT. Radar out of Bermuda shows the rains from Gert are staying just offshore, moving northward, parallel to the island. An Air Force hurricane hunter aircraft is in the storm, and has found that Gert has not changed much in intensity since last night. Top surface winds seen by their SFMR instrument this morning as of 10am EDT were 48 mph, though higher winds of 58 mph that may be erroneous due to rain interference were measured. It currently appears that Gert's northerly motion will keep virtually all of the storm's rains just offshore from from Bermuda. Gert should not trouble any land areas after moving past Bermuda.


Figure 1. Morning radar image of Gert from the Bermuda radar .

Elsewhere in the tropics
The disturbance we've been tracking over the past few days in the open Atlantic between Africa and the Lesser Antilles, Invest 93L, has regenerated a modest amount of heavy thunderstorms and will bring heavy rain showers and gusty winds to the Lesser Antilles today and Tuesday as it moves westwards through the islands at 15 - 20 mph. Dry air surrounds 93L, and is interfering with development. However, the disturbance is steadily moistening its environment and is under low wind shear of 5 - 10 knots, so could begin to organize over the next few days as it tracks across the Caribbean. The latest 06Z run of the NOGAPS model is showing weak development of 93L once it reaches the western Caribbean, with a track over Mexico's Yucatan Peninsula and into the Gulf of Mexico by this weekend. Stay tuned.


Figure 2. Radar-estimated rainfall for the past 2 days from the Long Island, NY radar.

New York City sets an all-time 1-day rainfall record
A long series of "training" thunderstorms that each moved along the same path deluged the New York City and Newark areas yesterday, smashing an all-time 1-day rainfall record at New York City's JFK Airport, which recorded 7.80 inches of rain. It was the most rain at JFK since record keeping began in 1948. The previous record was a 6.3" deluge on June 30, 1984. New York City's official measuring site, Central Park, got 5.81" yesterday, the fifth wettest day on record there. The 6.40" that fell on Newark, NJ yesterday was that city's 2nd heaviest 1-day rainfall in history, next to the 6.73" that fell on November 3, 1977.

Jeff Masters

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1438. Levi32
Quoting LowerCal:

Thank you so much. The instructions are comprehensive but brief and straightforward as is the script. You'd make a good Prof.

I'll be sure to send you a copy of changes, if any, I make for my purposes.


Glad it works! I forgot to mention that you have to have curl and imagemagick installed for it to work, but I think a lot of distributions carry those by default.
Member Since: November 24, 2005 Posts: 635 Comments: 26543
Quoting presslord:
Way cool space news Link


They finally announced COTS-2 and COTS-3 combining? That's excellent news!! Commercial crew here we come!
Member Since: July 8, 2005 Posts: 259 Comments: 23501
Quoting clwstmchasr:


IMO if 93L wants to develop it has to slow down which typically happens as it gets closer to the Western Caribbean.


Yes, I commented on that last night. 15 to 20 mph through the eastern Caribbean is not conducive to a wave trying to develop.
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Quoting Levi32:


You have mail. I have no idea how experienced you are with linux so I tried to include detailed instructions. It takes me 10 seconds to do it, so if it's difficult at first to give the correct inputs, just practice a couple times and I think you will find that it's pretty easy. Perhaps you will find a way to make my script even simpler than I currently have it. I'm fairly new to BASH.

Thank you so much. The instructions are comprehensive but brief and straightforward as is the script. You'd make a good Prof.

I'll be sure to send you a copy of changes, if any, I make for my purposes.
Member Since: Posts: Comments:
Quoting usa777:
Curios as to how they calculated the ACE value of a storm back in 1899?
Using the HURDAT file for maximum sustained winds. HURDAT goes back to 1851.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Quoting usa777:
Curios as to how they calculated the ACE value of a storm back in 1899?


It doesn't require a satellite or anything like that. All they need is lifespan and intensity at 6 hour intervals, and they have that for just about if not every storm in the database.
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Quoting kmanislander:
Apart from having expanded in aerial coverage I see no difference between 93L when it received 20% from the NHC and now. I would go for 20% and wait to see if the convection starts to rebuild before stepping it up to 30% later. Might as well join in the ratings game LOL
You nailed it, and I really suspect that's why the % stayed the same.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
1430. Levi32
Quoting usa777:
Curios as to how they calculated the ACE value of a storm back in 1899?


They have best-track data back through 1851 for Atlantic storms. They calculated the ACE based on the estimated 6-hourly intensities for that storm. Needless to say, the accuracy of the data for those storms back when observations were sparse is in question.
Member Since: November 24, 2005 Posts: 635 Comments: 26543
SHOWER AND THUNDERSTORM ACTIVITY HAS BECOME A LITTLE MORE
CONCENTRATED AND SLIGHTLY BETTER ORGANIZED IN ASSOCIATION WITH A
BROAD AREA OF LOW PRESSURE CENTERED ABOUT 400 MILES SOUTHEAST OF
ACAPULCO MEXICO. ENVIRONMENTAL CONDITIONS ARE FORECAST TO BE
MARGINALLY CONDUCIVE FOR THE DEVELOPMENT OF THIS DISTURBANCE...AND
A TROPICAL DEPRESSION COULD FORM DURING THE NEXT DAY OR TWO.
THIS SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

Member Since: July 17, 2010 Posts: 0 Comments: 81
1428. Patrap
Quoting kmanislander:
Apart from having expanded in aerial coverage I see no difference between 93L when it received 20% from the NHC and now. I would go for 20% and wait to see if the convection starts to rebuild before stepping it up to 30% later. Might as well join in the ratings game LOL




I always lacked skill with Lets Make a Deal.

Wrong curtain for me..

LoL
Member Since: July 3, 2005 Posts: 419 Comments: 127374
Quoting HurricaneDean07:
Thinking the piece that split from gert South of Cuba, will be mentioned as 10% at the next TWO, Maybe...


ULL is just to the SW of this AOI.
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Quoting stormpetrol:


Needless to say I totally agree though convection is not as strong, it has expanded in size and organized significantly since this morning in my opinion.
Still at 20%.
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1424. robj144
Quoting Levi32:


Um yeah it would. It means that a Cat 4 counts for even more points over a Cat 3 than the ACE would have given it.


Yes, I responded too fast.
Member Since: August 19, 2008 Posts: 0 Comments: 825

Atlantic Tropical Weather Outlook


000
ABNT20 KNHC 152338
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON AUG 15 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM GERT...LOCATED ABOUT 135 MILES EAST-NORTHEAST OF BERMUDA.

A TROPICAL WAVE IN THE VICINITY OF THE LESSER ANTILLES IS PRODUCING
A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS. THERE ARE NO
SIGNS OF A SURFACE CIRCULATION AT THIS TIME AND PRESSURES ARE NOT
FALLING SIGNIFICANTLY OVER THE AREA. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO BE MARGINALLY CONDUCIVE FOR DEVELOPMENT OF THIS SYSTEM
DURING THE NEXT COUPLE OF AS IT MOVES WESTWARD AT 15 TO 20 MPH OVER
THE CARIBBEAN SEA. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH


Only at 20%? Really?
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Quoting CybrTeddy:
TWO out, no change and virtually the same writing.



it this noted that so no point in posting it
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Quoting GeoffreyWPB:
A little more northerly component with 93L?



I think it's just the convection to the south dissipating and the convection to the north remaining providing an illusion that makes it look like it's starting to move more northerly.
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1420. usa777
Curios as to how they calculated the ACE value of a storm back in 1899?
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Quoting Patrap:
Anyone seeing those 4 big Cells off the Se Fla Coast this evening?





See them--went thru one of them! Lots of noise north and south of Stuart but minimumal rain, considering all the racket and the wind. Now to go out and pick-up all the palm fronds...........

Is it me, or when the thunderstorms develop west of Lake O and move east, they kind of split up, go around, and miss us. (We are on the coast, even with the top tip of Lake O.) We always seem to get missed when north and south are getting pounded.
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1418. Patrap
Models are tools,,never Gospel.


They show the trends thru time..and a comparing of the next to the last always gives us a Better understanding of what may occur downstream intime.

Consensus is the key,,

Take the 18Z Runs and compare to the 00Z runs coming out in a Hour or so.

Note the differnce between them and also the runs consensus.

Its showing Climatology as well as the current.

Thats a factor as well.

Thus the CLP series.

But pay attention to "consensus" its always the Canary in da tropical Mine.



18z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)



)
Dynamic Models (More sophisticated models)




Member Since: July 3, 2005 Posts: 419 Comments: 127374
A TROPICAL WAVE IN THE VICINITY OF THE LESSER ANTILLES IS PRODUCING
A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS. THERE ARE NO
SIGNS OF A SURFACE CIRCULATION AT THIS TIME AND PRESSURES ARE NOT
FALLING SIGNIFICANTLY OVER THE AREA. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO BE MARGINALLY CONDUCIVE FOR DEVELOPMENT OF THIS SYSTEM
DURING THE NEXT COUPLE OF AS IT MOVES WESTWARD AT 15 TO 20 MPH OVER
THE CARIBBEAN SEA. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
Member Since: July 17, 2010 Posts: 0 Comments: 81
TWO out, no change and virtually the same writing.
Member Since: July 8, 2005 Posts: 259 Comments: 23501
With the increase in vorticity we saw today, 93L is one sustained convective burst away from attempting to put out an LLC in my opinion. Although it hasn't really sustained convection it's whole life so we will see. By sustained I mean reaching beyond a diurnal cycle.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
1414. Levi32
Quoting robj144:


I haven't looked the Power Dissipation Index up just yet, but is there more to it than just using the cube of the velocity? That wouldn't qualitatively change the ACE.


It quantitatively changes it though. It means that a Cat 4 counts for even more points over a Cat 3 than the ACE would have given it. I guess there is a debate over which exponential function describes the power best.
Member Since: November 24, 2005 Posts: 635 Comments: 26543
Quoting MiamiHurricanes09:
African wave. The GFS has been showing no interest in developing 93L.


The GFS was all over developing 93L early on.
Member Since: Posts: Comments:
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON AUG 15 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM GERT...LOCATED ABOUT 135 MILES EAST-NORTHEAST OF BERMUDA.

A TROPICAL WAVE IN THE VICINITY OF THE LESSER ANTILLES IS PRODUCING
A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS. THERE ARE NO
SIGNS OF A SURFACE CIRCULATION AT THIS TIME AND PRESSURES ARE NOT
FALLING SIGNIFICANTLY OVER THE AREA. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO BE MARGINALLY CONDUCIVE FOR DEVELOPMENT OF THIS SYSTEM
DURING THE NEXT COUPLE OF AS IT MOVES WESTWARD AT 15 TO 20 MPH OVER
THE CARIBBEAN SEA. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

Member Since: Posts: Comments:
Apart from having expanded in aerial coverage I see no difference between 93L when it received 20% from the NHC and now. I would go for 20% and wait to see if the convection starts to rebuild before stepping it up to 30% later. Might as well join in the ratings game LOL
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Quoting xcool:


La Nina's return hmmmm
NOOOOOO!We need rain in Texas!
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A little more northerly component with 93L?

Member Since: September 10, 2007 Posts: 0 Comments: 10929
KHRM

Member Since: July 17, 2010 Posts: 0 Comments: 81
Way cool space news Link
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No mention of development but here is the PM discussion from Caribbean/NCEP desk on expected rainfall as 93L passes through:

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
305 PM EDT MON AUG 15 2011

TROPICAL WAVE ALONG 55W IS A FAIRLY PROGRESSIVE WAVE...AND IT IS LIKELY TO FAVOR SQUALLY WEATHER AS IT MOVES ACROSS THE NORTHEAST CARIBBEAN ISLANDS. SOME OF THE MODELS SHOW RISK OF SEVERE CONVECTION WITH THIS FEATURE...TO TRIGGER WATER SPOUTS AND STRONG GUSTY WINDS. IT IS TO FAVOR SCATTERED CONVECTION ACROSS THE ISLAND CHAIN THROUGH 42 HRS...WITH RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 25-50MM/DAY. ACROSS THE VIRGIN ISLES-PUERTO RICO IT WILL FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM/DAY THROUGH 42/48 HRS...WHILE OVER THE DOMINICAN REPUBLIC-HAITI IT IS
TO FAVOR ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. OVER JAMAICA IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. STRONG EASTERLIES ARE TO ACCOMPANY THIS FEATURE AS IT PROPAGATES ACROSS THE NORTHEAST CARIBBEAN...WITH
WINDS TO PEAK AT 20-25KT. STRONGER WINDS ARE EXPECTED ON ELEVATIONS ABOVE 2KM.




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1405. robj144
Quoting SouthDadeFish:
That's if the winds are equally spaced for both sets of data, etc. but yeah many interesting calculations can be done. You can also look into the Power Dissipation Index by Kerry Emanuel for more information. He thinks it is a better tool than ACE. It pretty much integrates all activity of the hurricane season using the cube rather than the square of the max winds.


I haven't looked the Power Dissipation Index up just yet, but is there more to it than just using the cube of the velocity? That wouldn't qualitatively change the ACE.
Member Since: August 19, 2008 Posts: 0 Comments: 825
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1403. xcool


La Nina's return hmmmm
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1402. zparkie
So far this year we have been blessed by some strange happenings in the atmosphere. Weak storm after weak storm, I hope this pattern continues, A storm looks strong and like its going to organize into a tight pattern with lots of convection, then all of a sudden in a few hours its scattered and lost its convection, the only storms hitting south florida are the afternoon thunder boomers sending down torrential down pours flooding streets and gusts of wind, then the sun comes out. Love south florida in the summer
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Not the worst signature I've seen.

Member Since: July 17, 2010 Posts: 0 Comments: 81
Quoting robj144:
So, just doing an extremely rough calculation, if one factors in the size of the wind field into the ACE, integrated ACE would depend on the size of the storm cubed. So, if one storm had wind field radius of hurricane winds that was twice the radius of another storm, but they both had the same max. winds, the larger storm has something on the order of 8 times more energy. This was very crude calculation that could be refined and made more sophisticated, however.
That's if the winds are equally spaced for both sets of data, etc. but yeah many interesting calculations can be done. You can also look into the Power Dissipation Index by Kerry Emanuel for more information. He thinks it is a better tool than ACE. It pretty much integrates all activity of the hurricane season using the cube rather than the square of the max winds.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Quoting nofailsafe:


Hm, there certainly is a little spin there.


also a low level spin just north of the SE Bahamas same loop

Link
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here's a avn image of the floater
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1397. Patrap
Quoting presslord:


I'd say there's a 50% or better chance you're right....


O I Hope so..,

bet the Haus,,Red
Member Since: July 3, 2005 Posts: 419 Comments: 127374
1396. GetReal
Quoting stormpetrol:
I would say 13.7N/61W is the possible COC of 93LLink



Hard to say IMO... There is very good ventilation at the upper levels, but very little cyclonic turning at the surface. 93L is moving quickly towards the west by WNW, and that fast pace is working against fast development. Hence I am not buying into the track nw towards the Bahamas, as of now. A weaker system will continue further west.

I do not see and rapid development with this system until it nears Jamaica.
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Quoting nofailsafe:


Hm, there certainly is a little spin there.


looks to be mid levels but yeah can see it for sure if you speed up the loop, pretty good bursts of convection nearby allso
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Good afternoon

93L has done a good job today during the heat and now Dmin. Now we watch to see if it can rebuild the deep convection lost since early this morning. If this system is true to historical form we should see blobs of deep convetion start to blow up in the next 6 hours or so.

The wave axis will soon enter the Caribbean which gives 93L about 180 miles to close off a surface low before the odds start to go against development in the short term.
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1393. Levi32
And just to show off.....here is the floater loop in GIF:

Member Since: November 24, 2005 Posts: 635 Comments: 26543
Thinking the piece that split from gert South of Cuba, will be mentioned as 10% at the next TWO, Maybe...
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Quoting serialteg:


ive probably told you this before (because im an old ranting fart) but, stay away from the models

:P

use them only for entertainment purposes


They are just guides... untrustable for considering Invests....

Although it is quite dificult to stay away from them... almost every animation, projected path, intensification table, etc. are based on them...

But you are right, they entertain....
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Quoting Saltydogbwi1:
Have not seen it mentioned as nothing will probably come of it but this little area just south of eastern cuba looks interesting

Link


Hm, there certainly is a little spin there.
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Quoting Patrap:


I rarely comment on NHC percentages,,if ever, but Im gonna say 93L the past 6 hrs has put some good work into bulding a better Haus,and a lil less into convection, and say we shall see 30% at the 8pm.

Structure sometimes preculdes convective cycles in the formative stage as 93L is undergoing.


I'd say there's a 50% or better chance you're right....
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Pretty cool simulated MW imagery from the HWRF

Member Since: July 17, 2010 Posts: 0 Comments: 81

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.