98L organizing; September temperatures in the U.S. return to normal

By: Dr. Jeff Masters , 1:29 PM GMT on September 20, 2011

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A tropical wave midway between Africa and the Lesser Antilles (Invest 98L) continues to look well-organized on satellite imagery, with a modest amount of heavy thunderstorm activity and excellent spin. An ASCAT pass from 7:47 pm EDT last night showed that 98L had a moderately well-defined surface circulation. Wind shear as diagnosed by the SHIPS model is light, less than 10 knots, and is predicted to stay light to moderate through Friday. Ocean temperatures are 28 - 28.5°C, well above the threshold typically needed for a tropical storm to spin up. Water vapor satellite images show 98L is embedded in a moist environment, but there is dry air to the system's northwest. However, given the light wind shear, this dry air may not pose a hindrance to development at this time. An analysis of upper level winds from the University of Wisconsin CIMMS group shows a pattern favorable for development, with an outflow channel open to both the north and south available to ventilate the storm and allow 98L to efficiently lift plenty of moisture to high levels.


Figure 1. Morning satellite image of 98L.

The models are not very aggressive about developing 98L into a tropical storm, but most of them do show some development. NHC gave the disturbance a 70% chance of developing into a tropical depression by Thursday in their 8 am Tropical Weather Outlook. 98L's westward motion of 5 - 10 mph should bring the storm into the Lesser Antilles Islands by Saturday, though the models are not in strong agreement about the forward speed of the storm. The GFDL model brings 98L into the islands on Friday, while the NOGAPS model keeps the storm east of the islands through Tuesday. If 98L takes a more west-northwesterly path through northern Lesser Antilles, which has been the preferred track for tropical systems this year, the disturbance should encounter high wind shear in excess of 20 knots due to strong upper-level winds out of the west. This shear should make it difficult for 98L to intensify as it moves though the islands. However, if 98L takes a more southerly path across Barbados, as predicted by the GFDL model, the storm will miss seeing the high shear area that lies over the northern islands, and the storm would have more opportunity to strengthen. The most likely scenario I see at this point is for 98L to be a weak tropical storm on Saturday as it moves through the Lesser Antilles--but there is more than the usual amount of uncertainty in both the track and intensity forecast.

September temperatures return to normal over the U.S.
The summer of 2011 was the second hottest in U.S. history, but September of 2011 is so far shaping up to be an average one for temperature. A series of cold fronts and cold-cored low pressure systems have moved southwards out of Canada this month, bringing typical amounts of cool air to the country. If you want to select dates for the start and end of the U.S. heat wave of 2011, the dates to pick would be May 20 - September 4. During the period May 20 - September 4, 2011, the number of daily record high temperatures at the 515 major airports in the U.S. exceeded the number of daily low temperature records every day but one. That's an astonishing 107 out of 108 days! Only July 15 had more record daily lows than highs during that 108-day period. I doubt one could find a similar stretch of days anytime in U.S. weather history where such a lopsided ratio of high temperature to low temperature records existed. For the 3-month summer period of June, July, and August, 2703 daily high temperature records were set, compared to 300 daily low temperature records--a ratio of 9-to-1. Not surprisingly, the summer of 2011 wound up as the hottest summer in 75 years in the U.S., and was only 0.1°F cooler than the all-time record hottest summer, during the Dust Bowl year of 1936. But so far this September, the ratio of high temperature records to low temperature records has been close to 1-to-1. There were 283 daily high temperature records set during the first sixteen days of September, and 246 low temperature records. Eight of the first sixteen days of September have seen the lows outnumber the highs, and eight have seen the highs outnumber the lows. The latest 2-week forecast from the GFS model shows a continuation of pretty normal weather over the U.S. for the rest of the month, and September temperatures will end up close to average.

Jeff Masters

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Quoting hydrus:
It seemed to have two centers there for a while...
possible it is kind of indicated on the vort maps
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Quoting Drakoen:
This morning's ASCAT pass reveals that 98L has a large circulation and is gonna need to tighten up a bit before significant development can take place.



yes that has been its problem all along
Member Since: September 19, 2005 Posts: 2 Comments: 4227
Obviously our weather records span a pretty laughable time frame when compared with the earth's geological time scale, but that isn't the point that is trying to be made here. If there is a run of records (# of cyclones, hot, cold, whatever) in the last 5 years of 120 years of data, that has a decent probability of indicating a trend. Not saying global warming is occurring, but you're just lying to yourself if you deny the importance of our weather records just because of the short time span.
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This morning's ASCAT pass reveals that 98L has a large circulation and is gonna need to tighten up a bit before significant development can take place.
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Quoting BobinTampa:



exactly, there is no open line of communication on EITHER side of this. So why do you clowns keep bogging down the blog trying to convince the unconvinceable?



+1,000,000
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Quoting caribbeantracker01:


i wonder where the center is actually located well i think it is where they said last but is organising some the cloud pattern represents a bit of struggle in the upper air imo see how there are clouds loking as if they are tired but i think the key thing is for it to get of the monsoonal trof
It seemed to have two centers there for a while...
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Quoting cmahan:
This obsession with perfect datasets is... interesting. Tell me, when was the last time we stuck a thermometer into the sun?
its not the accuracy its the length . Does it not bother anyone that we talk about records over the last 120 years out of 4 billion?
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49. Skyepony (Mod)
`
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i wonder where the center is actually located well i think it is where they said last but is organising some the cloud pattern represents a bit of struggle in the upper air imo see how there are clouds loking as if they are tired but i think the key thing is for it to get of the monsoonal trof
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Quoting Minnemike:
ok.. let's just throw out every other form of data that scores upon scores of geologist, chemists, and field researchers have discovered about previous climate.. oh yeah, and that notion that we evoloved is truly preposterous as well. there's no human recorded data that i know of pre-dating ancient scriptures.. and they certainly didn't mention that!

i'd avoid sarcasm if i thought there was a line of communication open on the other end..



exactly, there is no open line of communication on EITHER side of this. So why do you clowns keep bogging down the blog trying to convince the unconvinceable?
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Quoting Jax82:
120 years of data records
4,540,000,000 years of earth
ok.. let's just throw out every other form of data that scores upon scores of geologist, chemists, and field researchers have discovered about previous climate.. oh yeah, and that notion that we evoloved is truly preposterous as well. there's no human recorded data that i know of pre-dating ancient scriptures.. and they certainly didn't mention that!

i'd avoid sarcasm if i thought there was a line of communication open on the other end..
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Quoting ScottLincoln:


What period of data would you find reasonable to use as an indicator of climate?

According to the World Meteorological Organization, 30yrs makes a climate normal. According to most climate scientists, roughly a decade makes a duration to average out noise from solar cycles and other natural variations (weather vs. climate). According to statistics, the current rate of warming is statistically significant after roughly 15 years of data.

Why do you believe that these periods are not reasonable, and why do you believe that your period would be more reasonable than the ones determined by active scientists in the climate field?


Truthfully, I don't care about records. Why even have records, just take what Mother Nature dishes out. Does it really matter? There is no "normal" when it comes to weather. Do you get dressed each morning based on what the temperature is supposed to be or what it is forecast to be that day?
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Quoting floodzonenc:


LOL!!! Never stops being funny!
there is a bit of teleconnection to the w pac for a landfaller in that region dont count it out
Member Since: September 11, 2010 Posts: 1 Comments: 4589
Quoting Chucktown:


Except the record that you are breaking, hot or cold, is based on the past 120 years of data. For example, the record high here in Charleston, SC today is 98 degrees set in 1942. What if in 1345, it hit 102 here. Data set is too small to deduct what is going on when it comes to climate change.

Before this goes into another slug fest about global warming or climate change, I think (my opinion) was that Neapolitan was just quoting some facts about high temps that have been broken. I did not read anything into his post about climate change. I feel he was making an interesting observation regarding factual information about temps. And, thanks for that post.

Please guys, let's not start bickering today. Japan is facing a really bad situation with Typhoon Roke and those of us in S Fl, the Carib and gulf coast are intensely monitoring 98L.

Let's all just have a friendly tropical watching day. OK?
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Quoting Chucktown:


Except the record that you are breaking, hot or cold, is based on the past 120 years of data. For example, the record high here in Charleston, SC today is 98 degrees set in 1942. What if in 1345, it hit 102 here. Data set is too small to deduct what is going on when it comes to climate change.


What period of data would you find reasonable to use as an indicator of climate?

According to the World Meteorological Organization, 30yrs makes a climate normal. According to most climate scientists, roughly a decade makes a duration to average out noise from solar cycles and other natural variations (weather vs. climate). According to statistics, the current rate of warming is statistically significant after roughly 15 years of data.

Why do you believe that these periods are not reasonable, and why do you believe that your period would be more reasonable than the ones determined by active scientists in the climate field?
Member Since: September 28, 2002 Posts: 5 Comments: 3193
This obsession with perfect datasets is... interesting. Tell me, when was the last time we stuck a thermometer into the sun?
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Quoting Jax82:
120 years of data records
4,540,000,000 years of earth


Even the 120yrs sampling is so inaccurate.......its a joke honestly!
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Quoting TampaSpin:
COMPLETE Tropical UPDATE
Thanks for the update
Member Since: September 20, 2010 Posts: 0 Comments: 235
Quoting Chucktown:


Except the record that you are breaking, hot or cold, is based on the past 120 years of data. For example, the record high here in Charleston, SC today is 98 degrees set in 1942. What if in 1345, it hit 102 here. Data set is too small to deduct what is going on when it comes to climate change.
finally a good point as to the terribly small data set that dr. Masters keeps hyping. The earth is 4 billion years old to use a set of data collected over 120 years is not scientific or reasonable. Also our ability to collect accurate data has increased greatly over the last fifty years before that much of that data may be suspect.
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120 years of data records
4,540,000,000 years of earth
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COMPLETE Tropical UPDATE
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biowizard
you could be right 98L has it's sights on St Lucia, but i think it will pass in the channel between St Lucia and M artinique.
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Quoting Neapolitan:

To set a high temperature record means the temperature has to get hot enough to surpass the previous high temperature record (while, of course, setting a low temperature record means the temperature has to get cold enough to drop below the previous low temperature record). That's the situation regardless of season or geographical location; reaching a higher or lower temperature than ever before at a given station is a noteworthy event in and of itself.

But in reality we do not know if it is an all time record. Now do we? We don't have records from 400 years ago do we? I love it when someone says it is the hottest day in the last 40 years. Well what about the 1 million+ years before that are you really sure that day is the hottest all time?
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Things have not changed much with 97L the last few hrs. the satelite pictures indicate that the system continues to organise at a limited pace. there seems to signs of banding about to place in both the nort and soutn semi circles. The system is moving very slowly over very warm waters as well as very low wind shear which will help it to strenghn also. although most of the global models are at sea with the direction and intesity of 98L before it reaches the islands, my take is that the disturbance will move slightly north of due west and take the system into the central windward islands on sat as a weak tropical storm. one just has to look at the continuing west track of 99L which is to the northwest of 98L and determine it's future track
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Quoting TampaSpin:



That is also like saying this as an example is the 5th hottest month. So could it not be the 75th coolest month also. Just showing the spin one can do if you want too.

Well, that's quite an analogy. That's like saying the Super Bowl is a matchup between the 31st worst and 32nd worst teams in the NFL. ;-)
Member Since: November 8, 2009 Posts: 4 Comments: 13531
Quoting wxmobilejim:

That is like comparing apples to oranges of course you will most likely see more high temp. records broken than low temp. records in the summer because it is supposed to be hot. WOW some people amaze me in their trying to twist data to form into their own agendas.

To set a high temperature record means the temperature has to get hot enough to surpass the previous high temperature record (while, of course, setting a low temperature record means the temperature has to get cold enough to drop below the previous low temperature record). That's the situation regardless of season or geographical location; reaching a higher or lower temperature than ever before at a given station is a noteworthy event in and of itself.
Member Since: November 8, 2009 Posts: 4 Comments: 13531
Quoting Tango01:
Things are not looking good for Japan... Most of the towns in the Sanriku coast lost their seawalls from the tsunami and the coast sunk from the earthquake in March so any little storm surge will flood large portions of those coastal towns fighting to recover since March.

I am surprised Dr. Masters have not commented much about Typhoon Roke.


Looks like its gonna ride the Coast from South to North. If it stays just off shore the Storm Surge will be huge all the North.
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Things are not looking good for Japan... Most of the towns in the Sanriku coast lost their seawalls from the tsunami and the coast sunk from the earthquake in March so any little storm surge will flood large portions of those coastal towns fighting to recover since March.

I am surprised Dr. Masters have not commented much about Typhoon Roke.
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over 4 inches of rain for eastern NC..will be interesting to see if something develops off the east coast..

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Quoting HadesGodWyvern:
Japan Meteorological Agency
Tropical Cyclone Advisory #85
TYPHOON ROKE (T1115)
21:50 PM JST September 20 2011
===============================

SUBJECT: Category Four Typhoon In Sea South Of Japan

At 12:00 PM UTC, Typhoon Roke (940 hPa) located at 30.3N 133.6E has 10 minute sustained winds of 95 knots with gusts of 135 knots. The cyclone is reported as moving northeast at 15 knots

Dvorak Intensity: T6.0

Storm Force Winds
==================
80 NM from the center

Gale Force Winds
=================
280 NM from the center in southeast quadrant
200 NM from the center in northwest quadrant

Forecast and Intensity
=====================

24 HRS: 36.5N 139.3E - 65 knots (CAT 3/Strong Typhoon)
48 HRS: 46.7N 147.1E - Extratropical





My nephew is stationed at Yokasuka NAval Base and they are battening down the hatches. Looks like a beautiful storm on satellite.
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Quoting HadesGodWyvern:
Japan Meteorological Agency
Tropical Cyclone Advisory #85
TYPHOON ROKE (T1115)
21:50 PM JST September 20 2011
===============================

SUBJECT: Category Four Typhoon In Sea South Of Japan

At 12:00 PM UTC, Typhoon Roke (940 hPa) located at 30.3N 133.6E has 10 minute sustained winds of 95 knots with gusts of 135 knots. The cyclone is reported as moving northeast at 15 knots

Dvorak Intensity: T6.0

Storm Force Winds
==================
80 NM from the center

Gale Force Winds
=================
280 NM from the center in southeast quadrant
200 NM from the center in northwest quadrant

Forecast and Intensity
=====================

24 HRS: 36.5N 139.3E - 65 knots (CAT 3/Strong Typhoon)
48 HRS: 46.7N 147.1E - Extratropical



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The models for 98L seem to be wandering all over the place - but St Lucia seems to be in the sights at the moment ...

Brian
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Quoting wxmobilejim:

That is like comparing apples to oranges of course you will most likely see more high temp. records broken than low temp. records in the summer because it is supposed to be hot. WOW some people amaze me in their trying to twist data to form into their own agendas.



That is also like saying this as an example is the 5th hottest month. So could it not be the 75th coolest month also. Just showing the spin one can do if you want too.
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Quoting wxmobilejim:

That is like comparing apples to oranges of course you will most likely see more high temp. records broken than low temp. records in the summer because it is supposed to be hot. WOW some people amaze me in their trying to twist data to form into their own agendas.


Ya think..........LOL
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Need to watch the tailend of the front that is centered thru the GOM. Could be a spinner develop in that area very quickly.
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Quoting ackee:
which model solution do u buy for 98L

A GFS
B ECMWF
C NOSAPS
D GFDL
E HWRF
F CMC
The GFS or the GFDL...straight to Jam' LOL
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as long as ex 99 blowing smoke it still has a bit of a chance its struggling again as for 98 seems as if its moving very slow and latest image seems as if moving north a bit could be the camera up in space adjusting
Member Since: September 11, 2010 Posts: 1 Comments: 4589
Just went back 365 days on my weather calendar, I have received 9.50 inches of rain since last Sept. 20. I should have around 35 inches during that time frame. 7.3 inches this year and 2.2 from Sept 20, 2010 to end of the year. After Tropical Storm Hermine gave us good rains on Sept. 7, 2010 the rains just stopped.
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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.

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