A heat wave recap; generally quiet tropics

By: Dr. Jeff Masters , 4:45 PM GMT on July 25, 2011

Share this Blog
6
+

Last week's U.S. heat wave has finally subsided, and most of the Northeast will see some cool highs in the 70s today. Unfortunately, the Midwest, and mid-Atlantic will continue to see high temperatures in the 90s for the rest of this week, and the southern Plains will be forced to continue to endure triple-digits.

According to the National Climatic Data Center (NCDC), 2,100 daily high maximum temperature records have been set so far in July 2011, and 51% of those were set last week. 4,734 daily high minimum temperature records have been set so far this month, and 55% of those were set last week. Here's a breakdown of last week's records for the period July 18 through July 24:

High Maximum:

• 1,076 warmest maximum temperature for the date
• 90 warmest maximum temperature for the month of July
• 56 warmest maximum temperature of all time

High Minimum:

• 2,595 warmest minimum temperature for the date
• 207 warmest minimum temperature for the month of July
• 123 warmest minimum temperature of all time

The number of warm minimum temperatures is especially disturbing, as these tend to have more of an impact on health than the high maximums. When the temperature remains high at night, it prevents the body from being able to recover from the day's heat. According to NOAA, from July 1 through July 19, there were 22 heat-related deaths in the United States. Reuters is reporting that 34 deaths resulted from this heat wave. In an average year, heat remains the number one weather-related killer in this country. In some ways, the overnight low temperatures are the best way to quantify a heat wave, possibly even better than the heat index.


Figure 1. Map of daily high maximum temperature records for the period July 1 through July 25 from NCDC. Red circles without an X denote a broken record; red circles with an X denote a tied record.

Tropical Overview

The wave formerly known as Invest 90L

The wave formerly known as Invest 90L is moving slowly west through the Caribbean near Jamaica. A new burst of convection started this morning, which will undoubtedly produce some heavy rain over southern Cuba and Jamaica. While low-level circulation has remained about the same since late last week, the wave has become top-heavy with increased circulation at higher levels (700-500mb). None of the models (GFS, ECMWF, CMC, NGPS, UKMET) are developing this wave as tracks into the Gulf of Mexico, and they're all in agreement that the path will be toward far southern Texas or northern Mexico, except for the ECMWF deterministic run, which hints that it will take a turn toward the northern Gulf. However, this model hasn't shown actual development from the wave since Tuesday or Wednesday of last week.

NHC has dropped this invest as of Saturday afternoon, but it remains on their radar. They're giving the wave a 0% chance to form over the next 48 hours. Given the recent uptick in mid-level circulation, I'd imagine they're still a little concerned about the potential for this wave to fire-up again once it's in the Gulf, and it will surely be of concern for Cuba as it tracks westward. However, given the lack of model support for almost 7 days in a row now, I'd say this wave has seen its glory come and go.


Figure 2. Visible tropical Atlantic satellite captured at 11:14am EDT on Monday.

Other North Atlantic waves

There are a couple other waves to speak of that have left the coast of Africa in the past few days, one located near 40W and the other closer to Africa, around 30W, which is tangled up in the monsoon trough. The former is expected to take a southerly track, skirting northern South America, and possibly into the Bay of Campeche. Given this track, none of the models are suggesting it will develop. However, tropical cyclones that spin up in the Bay of Campeche generally have a short forecast lead time, so it's something to watch. The latter wave could take a slightly more northern track through the Caribbean islands, and a couple of the models seem to favor this wave for development at the end of their runs.

Tropical wave activity has been lacking so far this season, but climatologically we should see an increase in African easterly waves in August and September.

Angela

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 656 - 606

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47Blog Index

Member Since: Posts: Comments:
655. xcool
re-activate 90L COME soon
Member Since: Posts: Comments:
Quoting aislinnpaps:


Ahh, I thought she'd put her name on it. Threw me. Thanks.


She did.

"Tropical wave activity has been lacking so far this season, but climatologically we should see an increase in African easterly waves in August and September.

Angela"
Member Since: Posts: Comments:
Quoting aislinnpaps:


Ahh, I thought she'd put her name on it. Threw me. Thanks.


She did.
Member Since: Posts: Comments:
Quoting NICycloneChaser:


Not really sure how land could help a tropical system which fundamentally requires warm water to develop. And quite the opposite, actually, strong storms don't feel land so much whereas weaker ones tend to be damaged badly. For example, Bonnie last year was forecast to reach around 50-55mph before it reached Louisiana last July, but the passing over Florida killed it.


That's not true. As the case with 90L, if it were to go over land at this present time, how would land disrupt it more so than a hurricane with a well-defined circulation? As was the case with Bonnie, while not as developed as hurricanes, its circulation was well-defined, and land disrupted it severely.
Member Since: Posts: Comments:
649. xcool
any where from gulf mexico to Carribean hot spot this years look at ex 90L
Member Since: Posts: Comments:
Quoting TxHurricanedude11:

that wasnt the case it wasnt stacked al together so land disrupted more and also i think shear came in play as well.Back to the yucatan check what happen to pre arlene its circulation got slightly stronger and helped to be classified.If this were to sit over the yucatan then it would die but if it passes normally then the affect is hardly nothing.


But, at the same time, it would have little more than a day before it reached the Mexico/Texas coastline, which after a land passage is not likely to be enough time to develop. It's jmo, I could be wrong.
Member Since: Posts: Comments:
Current steering map. Please. I'm not on my computer that has the links.

Thanks!!!
Member Since: Posts: Comments:
Quoting TxHurricanedude11:

Its Angela that posted...Dr.Masters is on vacation.


Ahh, I thought she'd put her name on it. Threw me. Thanks.
Member Since: Posts: Comments:
Link
Member Since: Posts: Comments:
Quoting AtHomeInTX:
Woo Hoo! Something snuck under that ridge! Now if it just doesn't dry out before the rain hits the ground! :)



.. Significant weather advisory for Hardin... Jasper... Newton...
Jefferson and Orange counties... significant weather advisory for
Calcasieu Parish until 530 PM CDT...

At 429 PM CDT... National Weather Service meteorologists detected a
line of strong thunderstorms from 12 miles southwest of Lumberton to
6 miles south of Deweyville... moving south at 10 mph.

* The line of strong thunderstorms will be near...
Hartburg...
Mauriceville and Forest Heights...
Bevil Oaks and Pine Forest...
Vidor by...
Rose City and Beaumont...

These storms could produce rainfall amounts of one to two inches in a
short period of time... resulting in ponding of water around low lying
roadways. Remember... do not drive your vehicle into water covered
roadways.

Lat... Lon 3021 9438 3031 9373 3008 9366 3000 9427
Member Since: Posts: Comments:
Quoting angelafritz:
Convection around former 90L is looking decent, however, I think any circulation we're seeing is probably still at mid-levels. I don't quite understand what NHC means by "atmospheric conditions are not expected to be conducive." Deep layer shear isn't that high (there's a nice pocket of low shear along the expected path) and even though humidity is low in the Gulf in general, the wave has maintained it's high specific humidity (4 to 5 g/kg) throughout its lifetime, which is expected to stay with the wave as it crosses the Gulf. I think the kicker here is that mid-level vort is not translating to the surface.


I think it would be safe to say that whatever mid-level circulation we are following is at least trying to work down to the surface. 850 mb. vorticity has increased over the past few hours, a sign that something is trying to work its way down.

6 hours ago:



Now:

Member Since: Posts: Comments:
Quoting mcluvincane:

Sorry. I mean hurricane Don. It doesnt have the time.
Member Since: Posts: Comments:
ex90L is looking impressive look how its wraped around all the convection on visible images
Member Since: Posts: Comments:
Quoting cloudburst2011:
athome it looks like some rain is headed your way...i have received over 3 inches since 10am this morning...


Can you believe all of the rains missed me to the southwest! Lol. It's especially mean because I can hear it. Well I'm glad you got some rain. :)
Member Since: August 24, 2010 Posts: 0 Comments: 253
Member Since: Posts: Comments:
Quoting JrWeathermanFL:
Not goin to get Don out of this one.

Please explain why
Member Since: Posts: Comments:
632. bwi
Looks like pressure at Cayman Brac has dropped a bit -- hard to tell if that's just daily fluctuation or the disturbance. No wind shift though, at least not as of 4pm. http://www.wunderground.com/history/airport/MWCB/2 011/07/25/DailyHistory.html
Member Since: Posts: Comments:
ex-90L lookks like TS Nicole. lol
Member Since: Posts: Comments:
Quoting TxHurricanedude11:
Why would the yucatan kill it??Have u seen the last storms or waves that pass through it.What I've seen here is that it helps the wave cause the yucatan is flat.Btw if this was a strong storm then its inner core would be disrupted alot but not weak systems so will find out.


Not really sure how land could help a tropical system which fundamentally requires warm water to develop. And quite the opposite, actually, strong storms don't feel land so much whereas weaker ones tend to be damaged badly. For example, Bonnie last year was forecast to reach around 50-55mph before it reached Louisiana last July, but the passing over Florida killed it.
Member Since: Posts: Comments:
628. xcool
ex 90L looks better
Member Since: Posts: Comments:
Quoting angelafritz:
Convection around former 90L is looking decent, however, I think any circulation we're seeing is probably still at mid-levels. I don't quite understand what NHC means by "atmospheric conditions are not expected to be conducive." Deep layer shear isn't that high (there's a nice pocket of low shear along the expected path) and even though humidity is low in the Gulf in general, the wave has maintained it's high specific humidity (4 to 5 g/kg) throughout its lifetime, which is expected to stay with the wave as it crosses the Gulf. I think the kicker here is that mid-level vort is not translating to the surface.
Thanks Angela
Member Since: September 18, 2010 Posts: 0 Comments: 5248
Not goin to get Don out of this one.
Member Since: Posts: Comments:
625. skook
I was just thinking, it would be nice to see Angela( or Dr. Masters) be more active on the blog.. and viola!


thanks!
Member Since: Posts: Comments:
Folks need to understand if this thing gets going and a LLC goes, it's not gonna stop, it's gonna keep going and wont weaken till it hits land, the missing link is the LLC, once that forms, it's all in natures hands from there
Member Since: Posts: Comments:


Emergency workers block Fish Hatchery Road in Lacombe Monday, July 25, 2011, after run-off from heavy rains swept away a large culvert under the road, leaving the asphalt unsupported. A crew used heavy equipment to retrieve the culvert and place it on the bank. Traffic south of the break was diverted onto Pontchartrain Drive.
Member Since: Posts: Comments:
last two 850MB vorticity images.

1800 UTC



2100 UTC

Member Since: Posts: Comments:
Quoting RitaEvac:
90L looks better now than at any previous moment


Getting that cyclone symmetrical look imo.
Member Since: Posts: Comments:
Good afternoon/evening everyone. I was surprised to see Dr. Master's post. What happened to his vacation? We had a good almost ten minute downpour this morning. It was heavenly to listen to and watch out the window!
Member Since: Posts: Comments:
616. xcool
Member Since: Posts: Comments:


Quoting TxHurricanedude11:

850mb vorticity becoming better defined!
Member Since: Posts: Comments:
Woo Hoo! Something snuck under that ridge! Now if it just doesn't dry out before the rain hits the ground! :)



.. Significant weather advisory for Hardin... Jasper... Newton...
Jefferson and Orange counties... significant weather advisory for
Calcasieu Parish until 530 PM CDT...

At 429 PM CDT... National Weather Service meteorologists detected a
line of strong thunderstorms from 12 miles southwest of Lumberton to
6 miles south of Deweyville... moving south at 10 mph.

* The line of strong thunderstorms will be near...
Hartburg...
Mauriceville and Forest Heights...
Bevil Oaks and Pine Forest...
Vidor by...
Rose City and Beaumont...

These storms could produce rainfall amounts of one to two inches in a
short period of time... resulting in ponding of water around low lying
roadways. Remember... do not drive your vehicle into water covered
roadways.

Lat... Lon 3021 9438 3031 9373 3008 9366 3000 9427
Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting cloudburst2011:
nicyclone chaser thats imo...you believe what you want just look how it has developed in the last 12 hours from nothing last night to some strong convection good out flow and it does have a llc...i rest my case.


I know, everyone is entitled to their opinion. I just don't see this really getting going, UNLESS it misses or only skirts the Yucatan, in which case it may develop. It still has a long way to go and very little time before then.
Member Since: Posts: Comments:
I think 90L is going to ramp up quickly, as long as land interaction doesn't interfere. NHC could end up looking a bit silly with their 'near 0%' chance in the next 48 hours.

Link
Member Since: Posts: Comments:
Special Weather Statement:

...Wet conditions to persist across extreme southeast Louisiana
and coastal Mississippi through at least Friday...

A wet pattern will persist across southeast Louisiana and coastal
Mississippi through the week. Widespread showers and thunderstorms
are forecast to occur each day. With ample moisture in place...some
of these storms will be capable of producing brief periods of
locally heavy rainfall with rainfall rates as high as 2 to 3 inches
per hour.


Widespread flash flooding is not likely...so a Flash Flood Watch
is not warranted at this time. However...localized impacts such as
ponding of water on low lying roadways and in areas of poor drainage
can be expected in some areas each day. If conditions become more
favorable for widespread flash flooding...a Flash Flood Watch will
be issued at that time.

Most impacts will be minor...and will not pose a threat to life or
property assuming some caution is taken by the people in the
affected area. Most of these ponding impacts will be addressed
with Urban and Small Stream flood advisories. Flash flood warnings
will be issued if conditions appear to pose a significant threat
to life and property...such as homes or businesses likely to be
flooded...or closure of several roadways due to high water.

And, currently:


*atmo looks around for more fans to point NW*
Member Since: Posts: Comments:
We just had a light shower here, winds out of the S at maybe 10-15 mph... thought we would see a bit more action this p.m.



Forgot the imagery... lol
Member Since: Posts: Comments:
Angela "In some ways, the overnight low temperatures are the best way to quantify a heat wave, possibly even better than the heat index."

For everything except outdoor workers and possibly*farming, the overnight low is a better indicator of the degree of heat-related problems likely to arise than the daytime high.
The rate at which heat transfers between a heat source and a heat sink is proportional to the difference in temperature between the source and sink.
Buildings store heat during the day, and radiate&etc that stored heat during the night. A high overnight-low slows the rate at which a building can cool itself. And so during a heatwave, the building starts the next day warmer than the day before, and thus warms up faster (unless daytime temperature has decreased a lot).
Which increases heat stress upon folks who can't afford air conditioning, and increases the electricity bill for those who can.

That increased electricity bill derives from using more power, so electric companies have to produce more power to meet that demand, usually at a much higher price per kilowatt. The most expensive, the most inefficient, and the most polluting generator-plants are the ones fired up to produce peak-power when the demand peak greatly exceeds the average peak.
The extra pollution aggravates the medical problems brought on by heat stress. As well, it affects folks with other medical problems who can afford an air-conditioned lifestyle

The extra electricity being carried by powerlines heats up those powerlines to higher than normal temperatures. Which in turn increases the resistance of those powerlines to current flow. With more electrical power being wasted generating heat in those powerlines, even more generator-plants have to be called online.

Until eventually ya get to brownouts (when the voltage drops because of high demand, which causes an increased demand for current flow, which causes even more heating of the powerlines, which causes even more resistance to current flow within those powerlines, repeat...) and rolling blackouts (a decision to cut-off power to some sections of the grid to maintain a safe operating voltage on the rest of the grid) to prevent a total systems failure.

* Each plant enzyme has a specific temperature range in which it functions well. Exceed or fall beneath the ranges of those enzymes and the plant's metabolism goes into slowdown-to-shutdown mode. And unlike animals, most-approaching-all agriculturally-important plants have little means of controlling their internal temperatures.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
90L looks better now than at any previous moment
Member Since: Posts: Comments:

Viewing: 656 - 606

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47Blog Index

Top of Page

About

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

Local Weather

Overcast
30 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron