Weakening Typhoon Chan-hom Still a Major Storm Surge Threat for Shanghai

By: Jeff Masters , 4:08 PM GMT on July 10, 2015

Category 3 Typhoon Chan-hom is steadily weakening as it heads northwest at 10 mph towards China. The storm has slowed down and turned more to the north as it "feels" the steering influence of a trough of low pressure to its north, and the latest round of computer model forecasts have nudged the track of Chan-hom to the east, and it is possible that the center of Chan-hom will not make landfall in China. The 10 am EDT Friday forecast from the Joint Typhoon Warning Center (JTWC) and 8:50 am EDT Friday forecast from the Japan Meteorological Agency (JMA) predicted that Chan-hom would graze the coast of China and pass close to or just offshore from Shanghai on Saturday evening local time (Saturday morning in the U.S.) On this path, Shanghai, China's most populous city with 23 million people in the metro area, would be on the weak side of the storm, and receive only modest wind damage and heavy rain. However, Chan-hom would still drive a large storm surge into Shanghai, and this storm surge could be one of the highest ever observed, equivalent to a 1-in-200 year flood. Even though Chan-hom is weakening due to cooler waters and interaction with land, part of the weakening is due to an eyewall replacement cycle, where the inner eyewall collapses and is replaced by a larger-diameter outer eyewall. While this process weakens the peak winds near the center, it spreads the typhoon-strength winds over a larger area, increasing the size of the storm surge.


Figure 1. Typhoon Chan-hom as seen by the MODIS instrument on NASA's Aqua satellite at approximately 10 pm EDT Thursday, July 9, 2015 (02 UTC.) At the time, Chan-hom was a weakening Category 4 storm with winds of about 130 mph. Image credit: NASA Worldview.

Chan-hom's storm surge
Chan-hom is a very large typhoon with tropical-storm force winds that extended outwards up to 310 miles from the center, which will pile up a large storm surge throughout the Yellow Sea, from China to the Korean Peninsula. Since the Yellow Sea is shallow and enclosed on three sides, this water will be forced up onto land over Shanghai as Chan-hom makes its closest approach. In their 10 am EDT Friday forecast, JTWC predicted that Chan-hom would be a Category 1 storm with 80 mph winds (1-minute average) at 12 UTC Saturday, which would make it just 5 mph weaker than the strongest landfalling storm to hit within 200 miles of Shanghai in the past 35 years, Typhoon Winnie of August 1997. As I discussed in detail in my previous post, the storm surge from Winnie was only 5.5" (14 cm) below the top of the 19.2-foot (5.86 meter) Suzhou Creek floodgate that protects downtown Shanghai.

Low tide in Shanghai is at 07:07 UTC Saturday, and high tide is at 12:48 UTC Saturday, at a time when the center of Chan-hom is predicted to be 20 - 80 miles south of the city. Thus, the counter-clockwise circulation around the center will be pushing water into the city at high tide. Fortunately, this high tide is not a very high one--high tides late next week will be more than two feet higher than this. Though Chan-hom will be weakening as it approaches Shanghai during Saturday's high tide, the typhoon will be capable of pushing a record-size storm surge into the city during this 12:48 UTC Saturday high tide. I've read several studies explaining how storm surge propagation in the Yellow Sea is extremely complicated, so I am unsure just how the great the risk is from this storm without seeing data from a sophisticated real-time storm surge model.



Figure 2. Predicted swath of winds (top) and precipitation (bottom) for Typhoon Chan-hom, made by the 06 UTC (2 am EDT) Friday, July 10 run of the HWRF model. The model predicted that Chan-hom would graze the coast near Shanghai as a strong tropical storm, bringing rainfall amounts of 4 - 8" near the coast (dark yellow colors), and 2 - 4" farther inland. The typhoon was also forecast to bring large areas of 4 - 8" of rain to North Korea, which is suffering one of its worst droughts on record. Image credit: NOAA.

Chan-hom's rains and winds
With the latest round of model runs showing the Chan-hom will not penetrate far inland, wind damage is looking to be less of a concern, since most of the land areas affected will be on the weaker (left) side of the eye. The prospect for heavy damage due to flooding from torrential rains is also looking lower, as Chan-hom may only dump heavy rains of 4 - 8" along the immediate coast (Figure 2.) As Chan-hom turns to the north, it is expected to track over North Korea, which could use the rain--they have reportedly been suffering through their worst drought in 100 years, though rains in June have likely eased the drought.


Figure 3. Tracks of all typhoons with at least 75 mph winds (10-minute average winds as rated by the Japan Meteorological Agency) to pass within a 230-mile diameter circle (light shaded region) near Shanghai, China. Typhoon Winnie is labeled in white. Ten-minute average winds of 75 mph are roughly equivalent to 85 mph winds for the one-minute averaging time winds used for the U.S. Saffir-Simpson scale. All of the storms in this plot had sustained 10-minute average winds of 75 mph or less when they made landfall. Image credit: NOAA.

Strong typhoons hitting near Shanghai: a rare occurrence
China gets hit by about nine tropical cyclones (tropical depression, tropical storms, or typhoons) each year (Chen, 2000), but these strikes occur primarily in the southern portion of the country. The Jiangsu Province where Shanghai lies received only seven landfalls in the 50-year period 1947 - 1999, so the region does not have a lot of typhoon experience. Since 1979, no typhoon with winds in excess of about 85 mph (75 mph winds using a 10-minute averaging time) has made landfall within about 200 miles of Shanghai (Figure 2.) Historically, the strongest typhoon to affect the city in the past century may be Typhoon Gloria of July 24 - 25, 1949, whose storm surge overwhelmed the city's flood walls and left much of Shanghai a flooded ruin, with over 250,000 people homeless (See David Longshore's Encyclopedia of Hurricanes, Typhoons, and Cyclones). Note that Typhoon Wanda of 1956 was at Category 3 strength when it hit the coast of China about 100 miles south of Shanghai. Wanda killed 2000 people in China. China has had four typhoons that have killed at least 37,000 people each--most recently in 1975, when torrential rains from what had been Super Typhoon Nina caused the Banqiao Dam to fail, killing 90,000 - 230,000 people.

Links
The new Japanese Himawari satellite has some spectacular imagery of Chan-hom (Sector 4 in Band 3=visible, and Sector 6 in Band 13=IR.)

Chan-hom satellite imagery from NOAA/NESDIS.

Weather radar from China.

Shanghai webcams (thanks to wunderground member fuzed for posting this link.)

Wunderblogger Steve Gregory has the latest on the status of El Niño in his latest post.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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251. chasSoCal
6:26 PM GMT on July 11, 2015
Quoting 245. Patrap:


Don't worry there, He is completely WRONG.

Imagine the Solar output reduce by 60%.

Think what would happen.

And how does one "throttle down by 60%" a Fusion fueled Yellow Star on Main Sequence ?


The mainstream astronomy is surprisingly persistent in its ignorance of explanation, what drives the Solar dynamo - the changes of barycenter location of Solar system with massive planets. It just looks like another taboo of mainstream physics for me. Its ignorance is the more surprising, as this explanation doesn't threat the established physical theories very much - with the only honor exception: the Arrhenius model of global warming. And this is IMO the rub of this ignorance: the NASA, which is motivated to solar research the most is also engaged in anthropocentric global warming model


That is Lunacy.
Quoting 201. yonzabam:

Earth heading for a mini ice age within 15 years

Incredible that this gets on to the front page of the UK Telegraph. The depths of scientific illiteracy are plumbed with the statement that solar output 'will decline by 60%'. Of course, this means that the oceans will freeze solid and all life on Earth will cease to exist. Still, in the short time we have left, we can stop fretting about global warming. Every cloud etc.

Link


From the R.A.S. site the paper is a bit different. I believe what they are saying is that the variability of the sun over its normal 11 year cycle will be reduced, not the overall output of the sun.

Link
Member Since: December 31, 1969 Posts: Comments:
250. JohnLonergan
4:24 PM GMT on July 11, 2015
Quoting 237. etxwx:



Prof Valentina Zharkova's research was presented at the National Astronomy Meeting 2015 in Llandudno, North Wales and is also being reported on
ScienceDaily: Solar activity predicted to fall 60% in 2030s, to 'mini ice age' levels: Sun driven by double dynamo
and
Physics.org: Irregular heartbeat of the Sun driven by double dynamo

It will be interesting to follow up on the reception of this.



It'll be no big deal, except with the denier fringe who will misinterpret the study.

A major point of cofusion is that solar activity means sunspot activity, not solar energy output.
In light of this Dr. Zharkova predicts sunspot activity similar to the Maunder minimum. A similar prediction was made at a 2014 meting of During a meeting of the Solar Physics Division of the American Astronomical Society.

Dr. Georg Feulner of Potsdam Institute for Climate Impact Research wrote a response at RealClimate.

An analysis of historic sunspot observations shows that the 11-year solar activity cycle was interrupted during the late 17th century.
This period of time, during which the Sun appeared without sunspots most of the time, was called the Maunder Minimum by Jack Eddy in his famous Science paper. (Alliteratively named after Edward Maunder, although it was actually first discovered by Gustav Spörer.)


Figure 3: Observations of the number of sunspots over the last four centuries. Source: Wikimedia Commons/Global Warming Art.

...It remains to be seen whether this prognosis turns out to be true (there have been some doubts expressed), but since grand minima of solar activity did occur in the past, it is certainly interesting to explore what effects such a minimum might have on 21st century climate if it did occur. This is precisely the question Stefan Rahmstorf and I investigated in a study published last year (see also our press release. (Earlier estimates for the size of this effect can be found here and here.) In our study we find that a new Maunder Minimum would lead to a cooling of 0.3°C in the year 2100 at most – relative to an expected anthropogenic warming of around 4°C. (The amount of warming in the 21st century depends on assumptions about future emissions, of course).



Figure 4: Rise of global temperature (relative to 1961-1990) until the year 2100 for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. Source: PIK.

According to these results, a 21st-century Maunder Minimum would only slightly diminish future warming. Moreover, it would be only a temporary effect since all known grand solar minima have only lasted for a few decades.


So I can dig out my ClimateCrocks video from 2014.(Warning: video starts with very disturbing image.)
Member Since: December 31, 1969 Posts: Comments:
249. WunderAlertBot (Admin)
4:21 PM GMT on July 11, 2015
JeffMasters has created a new entry.
248. Patrap
4:17 PM GMT on July 11, 2015
A nice long radar loop of the Typhoon's approach and now exit to the NNE as forecasted.

The angle of impact was the best one for a smaller surge as the Storm only sideswiped the Coastal areas at a oblique angle, rather than a straightforward impact.


Quoting 134. barbamz:

Approaching landfall while the eyewall has opened up.

Loop courtesy of: Brian McNoldy, Univ. of Miami, Rosenstiel School



Member Since: December 31, 1969 Posts: Comments:
247. Envoirment
4:11 PM GMT on July 11, 2015
Nangka:



Currently under moderate-high shear on its northwestern quadrant which seems to be driving dry air into the system and impeding re-strengthening. Shear is expected to decrease over the next couple days and both the GFS & Euro have the storm becoming a category 5 and landfalling in mainland Japan as a major:







Member Since: December 31, 1969 Posts: Comments:
246. Patrap
4:00 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
245. Patrap
3:56 PM GMT on July 11, 2015
Quoting 238. JustDucky251:



Let us heartily hope that the Professor's calcs are wrong.

Don't worry there, He is completely WRONG.

Imagine the Solar output reduce by 60%.

Think what would happen.

And how does one "throttle down by 60%" a Fusion fueled Yellow Star on Main Sequence ?


The mainstream astronomy is surprisingly persistent in its ignorance of explanation, what drives the Solar dynamo - the changes of barycenter location of Solar system with massive planets. It just looks like another taboo of mainstream physics for me. Its ignorance is the more surprising, as this explanation doesn't threat the established physical theories very much - with the only honor exception: the Arrhenius model of global warming. And this is IMO the rub of this ignorance: the NASA, which is motivated to solar research the most is also engaged in anthropocentric global warming model


That is Lunacy.
Member Since: December 31, 1969 Posts: Comments:
244. islander101010
3:41 PM GMT on July 11, 2015
buildup of convection near the s. bahamas and hispanola hopefully puerto rico gets a bit too
Member Since: December 31, 1969 Posts: Comments:
243. LargoFl
3:36 PM GMT on July 11, 2015

HEAT ADVISORY
Issue Date: 224 AM EDT SAT JUL 11 2015
Expiration: 800 PM EDT SAT JUL 11 2015
...HEAT ADVISORY IN EFFECT TODAY FOR PARTS OF SOUTHWEST
GEORGIA AND THE FLORIDA BIG BEND AND ADJACENT PORTIONS OF
SOUTHEAST ALABAMA AND THE EASTERN PANHANDLE...

ALZ067-069-FLZ011-013-015>017-026-027-115-127-GAZ 120>125-142>145-
155>157-120000-
/O.NEW.KTAE.HT.Y.0003.150711T1500Z-150712T0000Z/
HENRY-HOUSTON-JACKSON-CALHOUN-INLAND FRANKLIN-GADSDEN-LEON-
LIBERTY-INLAND WAKULLA-COASTAL FRANKLIN-COASTAL WAKULLA-QUITMAN-
CLAY-RANDOLPH-TERRELL-DOUGHERTY-EARLY-MILLER-BAKE R-MITCHELL-
SEMINOLE-DECATUR-GRADY-
INCLUDING THE CITIES OF...HEADLAND...ABBEVILLE...TAYLOR...
ASHFORD...KINSEY...COWARTS...WEBB...COTTONWOOD... REHOBETH...
MARIANNA...GRACEVILLE...MALONE...SNEADS...BLOUNTS TOWN...
APALACHICOLA...CARRABELLE...QUINCY...CHATTAHOOCHE E...
TALLAHASSEE...SPRING HILL...SWEETWATER...SOPCHOPPY...ST. MARKS...
GEORGETOWN...FORT GAINES...CUTHBERT...SHELLMAN...ARLINGTON...
MORGAN...EDISON...LEARY...DAWSON...ALBANY...DOUGL ASVILLE...
BLAKELY...COLQUITT...NEWTON...CAMILLA...PELHAM... DONALSONVILLE...
BAINBRIDGE...CAIRO
224 AM EDT SAT JUL 11 2015 /124 AM CDT SAT JUL 11 2015/



...HEAT ADVISORY IN EFFECT FROM 11 AM EDT /10 AM CDT/ THIS
MORNING TO 8 PM EDT /7 PM CDT/ THIS EVENING...

THE NATIONAL WEATHER SERVICE IN TALLAHASSEE HAS ISSUED A HEAT
ADVISORY...WHICH IS IN EFFECT FROM 11 AM EDT /10 AM CDT/ THIS
MORNING TO 8 PM EDT /7 PM CDT/ THIS EVENING.

* TEMPERATURE...HIGHS IN THE UPPER 90S INLAND AND THE LOWER TO MID
90S NEAR THE COAST.

* HEAT INDEX...UP TO 109 OR 110 DEGREES IN SOME AREAS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HEAT ADVISORY MEANS THAT A PERIOD OF HOT TEMPERATURES AND HIGH
HUMIDITY WILL CREATE A SITUATION IN WHICH HEAT ILLNESSES ARE
POSSIBLE. DRINK PLENTY OF FLUIDS...STAY IN AN AIR-CONDITIONED
ROOM...STAY OUT OF THE SUN...AND CHECK UP ON RELATIVES AND
NEIGHBORS. IF YOU WORK OR SPEND TIME OUTSIDE. WHEN POSSIBLE...
RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING OR EVENING. KNOW
THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION AND HEAT STROKE. HEAT
STROKE IS AN EMERGENCY...CALL 9 1 1.



Member Since: December 31, 1969 Posts: Comments:
242. ColoradoBob1
3:31 PM GMT on July 11, 2015


Solved? How scientists say mystery craters were formed in northern Siberia

A new expedition to the craters in Yamal, in northern Russia, shows how they have rapidly altered since they were first noticed last year, but also indicates the possibility that not all the craters were formed in identical ways. The holes – first noticed last year – intrigued and perplexed scientists from around the world, initially provoking a number of explanations as to their cause, the most outlandish of which was that they were caused by stray missiles or even aliens from outer space.

Now the experts say the formation is something ‘never observed’ before, linked to warm weather in recent years. New pictures from the expedition are shown here, showing how one of the holes has rapidly filled with water in recent months.


Link
Member Since: December 31, 1969 Posts: Comments:
241. Climate175
3:30 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
240. Climate175
3:26 PM GMT on July 11, 2015
Quoting 239. washingtonian115:


Remember Alberto? Was a blog that morning and went on to be a 60mph storm tat afternoon xD.
Yep LOL, we may be looking at the same scenario, it may go from blob to tropical storm real quick!
Member Since: December 31, 1969 Posts: Comments:
239. washingtonian115
3:23 PM GMT on July 11, 2015
Quoting 233. Climate175:



Remember Alberto? Was a blog that morning and went on to be a 60mph storm tat afternoon xD.
Member Since: December 31, 1969 Posts: Comments:
238. JustDucky251
3:18 PM GMT on July 11, 2015
Quoting 237. etxwx:



Prof Valentina Zharkova's research was presented at the National Astronomy Meeting 2015 in Llandudno, North Wales and is also being reported on
ScienceDaily: Solar activity predicted to fall 60% in 2030s, to 'mini ice age' levels: Sun driven by double dynamo
and
Physics.org: Irregular heartbeat of the Sun driven by double dynamo

It will be interesting to follow up on the reception of this.



Let us heartily hope that the Professor's calcs are wrong.
Member Since: December 31, 1969 Posts: Comments:
237. etxwx
3:17 PM GMT on July 11, 2015
Quoting 201. yonzabam:

Earth heading for a mini ice age within 15 years

Incredible that this gets on to the front page of the UK Telegraph. The depths of scientific illiteracy are plumbed with the statement that solar output 'will decline by 60%'. Of course, this means that the oceans will freeze solid and all life on Earth will cease to exist. Still, in the short time we have left, we can stop fretting about global warming. Every cloud etc.

Link


Prof Valentina Zharkova's research was presented at the National Astronomy Meeting 2015 in Llandudno, North Wales and is also being reported on
ScienceDaily: Solar activity predicted to fall 60% in 2030s, to 'mini ice age' levels: Sun driven by double dynamo
and
Physics.org: Irregular heartbeat of the Sun driven by double dynamo

It will be interesting to follow up on the reception of this.
Member Since: December 31, 1969 Posts: Comments:
236. whitewabit
3:17 PM GMT on July 11, 2015
Quoting 234. PlazaRed:

About 9 pm local time now in the Shanghai area.
They have probably been experiencing 24 hours of really bad weather by now including at least 2 high tides.
according to the Internet media about a million people have been evacuated but where too is not quite clear, this might mean they have been moved across the road or into a higher apartment in their blocks.

So far there seems to be very little real news even on here, so I suppose that speculation will rule the day, or the night as the case may be.

35/C in Spain at the moment. The weather team says that we might cool off a bit in a week or so. Meanwhile they have come up with a new "chart," which shows that the waves of heat which we always experience during the summer here have lengthened quite considerably from a few days last "centaury," to levels of up to 18 days in the last 15 years.
Sort of interesting and I'm sure worth a bit more study. The recent Texas heat wave was very long and there are probably a lot more out there waiting to be noted.
This could be a symptom of climate change and heating of certain areas exemplified by much longer heat waves, plus new long term high heat waves in areas not previously affected by them.


Local Shanghai weather report is saying 73 degrees with the wind from the NNW at 18 .. and Rain
Member Since: December 31, 1969 Posts: Comments:
235. JustDucky251
3:16 PM GMT on July 11, 2015
Quoting 202. NativeSun:

A couple years, does not make a pattern change.


When I moved down to Mobile from Boston in '02, everything was brown. There had been little rain for several years and it showed. The vegetation was brown and dying and the soil was hard as a rock. It stayed that way for another year. Then WHAM the rains came and everything turned green. Now it is so green that it is difficult to remember the brown. These things cycle. Just wait.
Member Since: December 31, 1969 Posts: Comments:
234. PlazaRed
3:08 PM GMT on July 11, 2015
About 9 pm local time now in the Shanghai area.
They have probably been experiencing 24 hours of really bad weather by now including at least 2 high tides.
according to the Internet media about a million people have been evacuated but where too is not quite clear, this might mean they have been moved across the road or into a higher apartment in their blocks.

So far there seems to be very little real news even on here, so I suppose that speculation will rule the day, or the night as the case may be.

35/C in Spain at the moment. The weather team says that we might cool off a bit in a week or so. Meanwhile they have come up with a new "chart," which shows that the waves of heat which we always experience during the summer here have lengthened quite considerably from a few days last "centaury," to levels of up to 18 days in the last 15 years.
Sort of interesting and I'm sure worth a bit more study. The recent Texas heat wave was very long and there are probably a lot more out there waiting to be noted.
This could be a symptom of climate change and heating of certain areas exemplified by much longer heat waves, plus new long term high heat waves in areas not previously affected by them.
Member Since: December 31, 1969 Posts: Comments:
233. Climate175
3:05 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
232. JustDucky251
3:00 PM GMT on July 11, 2015
Quoting 169. sar2401:

It looks like you are trying to link from a mobile site. That doesn't work here. I assume this is the Accuweather page you mean. Yeah, that low has possibilities depending on when it gets off the coast and where. I don't give it more than a 30% chance of becoming anything tropical now but we'll see.


It looks like the tropical waves are finally getting to the Antilles. Up until now that have been turned back before getting there. The season may be getting ready for action.
Member Since: December 31, 1969 Posts: Comments:
231. washingtonian115
2:53 PM GMT on July 11, 2015
Now hopefully future Claudette stays off shore...Its to early for a storm to be running up the coast.But then again it has been unusually wet around here lately and that seems to attract T.C's.
Member Since: December 31, 1969 Posts: Comments:
230. CybrTeddy
2:48 PM GMT on July 11, 2015
Quoting 226. ncstorm:

Aww Teddy..you beat me to it..LOL


But to answer your question, it appears to be a fully tropical moderate tropical storm.
Member Since: December 31, 1969 Posts: Comments:
229. georgevandenberghe
2:43 PM GMT on July 11, 2015
Quoting 219. Climate175:

Even better! It can sometimes even snow in October, even though it's rare. We usually get the first snow flurries around in mid-late November.


I've never had to deal with disrupting or crippling snow in October. The Veterans day storm stopped me a mile from home. I didn't want to deal with the final 5% hill down into my apartment complex so I just gave up, buried the car
in a drift off the road and walked the rest of the way. I dug out the next morning.
Member Since: December 31, 1969 Posts: Comments:
228. georgevandenberghe
2:40 PM GMT on July 11, 2015
Quoting 222. Xyrus2000:



Correct, seconds. That's what I get for posting late at night. :D

The same issues occur with climate models. Actually with climate models it's even worse as they're typically run for months at a time so those tiny deviations accumulate.


Some years ago I took the GFS 64 bit initial conditions, truncated to 32 bit (it supports both forms of input) and did two low resolution runs with the different
IC. You couldn't see the difference with the naked eye on charts for about five days. By 20 days, the two forecasts could not be recognized as coming from the same initial time. The GFS does most of its calculations with 64 bit real and complex numbers.
Member Since: December 31, 1969 Posts: Comments:
227. islander101010
2:19 PM GMT on July 11, 2015
model failure again they had chan horn well inland. hope same thing like this does not happen to us again in e. cen fl.
Member Since: December 31, 1969 Posts: Comments:
226. ncstorm
2:12 PM GMT on July 11, 2015
Aww Teddy..you beat me to it..LOL
Member Since: December 31, 1969 Posts: Comments:
225. ncstorm
2:12 PM GMT on July 11, 2015
anyone see the 00z Euro..not sure if tropical or not



Member Since: December 31, 1969 Posts: Comments:
224. CybrTeddy
2:09 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
223. ncstorm
2:03 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
222. Xyrus2000
2:02 PM GMT on July 11, 2015
Quoting 212. georgevandenberghe:



Its seconds. Otherwise.. yep.

Most reproducibility issues come from nondeterministic ordering of calculations creating race conditions for when an operand is used. You are right also that this is scientifically okay in a weather model but makes validation of correctness of a change MUCH more difficult. So we insist on exact reproducibility. That makes debugging MUCH easier. The Intel compiler (NCEP uses Intel "Sandybridge" chips) has options that disable calculation reordering.. (-fp-model strict)
(that was the one with the POWER3/4/5/6/ xlf compiler also). The performance penalty using this is a few percent.

The MPI-1 (and followups) standard also encourages performance over reproducibiltity and reduction order in particular is likely to change from run to run. When users ask me how to fix this (besides getting on the standards committee) I tell them to either

1. Do reductions in quad precision and copy results to the precision of the rest of the model.
2. Normalize, do reductions in integer (guaranteed exact) and convert back to real and denormalize.
3. Write your own MPI reductions (that's easier than you think BTW)

Most users choose option 1. Fortunately with our implementation, reduction order is guaranteed if the decomposition doesn't change.



Correct, seconds. That's what I get for posting late at night. :D

The same issues occur with climate models. Actually with climate models it's even worse as they're typically run for months at a time so those tiny deviations accumulate.
Member Since: December 31, 1969 Posts: Comments:
221. ncstorm
2:01 PM GMT on July 11, 2015
Good Morning everyone..beautiful morning here in eastern NC

Member Since: December 31, 1969 Posts: Comments:
220. Patrap
1:53 PM GMT on July 11, 2015

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 11 JUL 2015 Time : 130000 UTC
Lat : 30:30:57 N Lon : 122:52:29 E


CI# /Pressure/ Vmax

3.5 / 973.2mb/ 55.0kt


Final T# Adj T# Raw T#
2.8 2.6 2.1

Center Temp : -12.4C Cloud Region Temp : -26.3C

Scene Type : CURVED BAND with 0.38 ARC in MD GRAY
Maximum CURVED BAND with 0.52 ARC in MD GRAY
at Lat: 29:54:35 N Lon: 122:52:12 E

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr

Weakening Flag : ON
Rapid Dissipation Flag : FLAG

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 160km
- Environmental MSLP : 1000mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 42.9 degrees
Member Since: December 31, 1969 Posts: Comments:
219. Climate175
1:50 PM GMT on July 11, 2015
Quoting 217. georgevandenberghe:



Remembering the Veterans day 1987 snow dump... Four more months!
Even better! It can sometimes even snow in October, even though it's rare. We usually get the first snow flurries around in mid-late November.
Member Since: December 31, 1969 Posts: Comments:
218. Patrap
1:50 PM GMT on July 11, 2015
Member Since: December 31, 1969 Posts: Comments:
217. georgevandenberghe
1:48 PM GMT on July 11, 2015
Quoting 215. Climate175:

5 more months til the Winter Fun begins!


Remembering the Veterans day 1987 snow dump... Four more months!
Member Since: December 31, 1969 Posts: Comments:
216. georgevandenberghe
1:47 PM GMT on July 11, 2015
Quoting 205. intampa:

something needs to happen. the heat and lack of rain here just east of tampa is frustrating and the plants are not liking it much either. seems we no longer have those "regular" afternoon showers that seemed to cover a lot more area like years past. its very scattered and usually I75 east. the spots that get it really get it but when its so hot and showers so scattered just doesnt seem like the rainy seasons of years past and thats been the way a few years now.


I remember both summers I spent in Tallahassee were hot and soggy (after dry springs and followed by dry falls). It would have been interesting to try to grow things there last year when they had their driest JJA of record with only a few inches each summer month.

Member Since: December 31, 1969 Posts: Comments:
215. Climate175
1:44 PM GMT on July 11, 2015
Quoting 214. georgevandenberghe:

One of my rules of thumb (acronym ROT from John Dutton, a PSU professor of mine)
is that severe weather season for the Mid Atlantic pretty much ends until September
as of July 10.

Well happy today! Frequency does drop off sharply about this time of year as we lose dynamics
and fronts start having trouble getting here as anything more than windshifts and 1C dewpoint drops. Second
season begins last week in August through October.

Yeah gross oversimplification esp.. this year when it looks like we'll still have westerlies but the rule holds a surprising fraction of summers
5 more months til the Winter Fun begins!
Member Since: December 31, 1969 Posts: Comments:
214. georgevandenberghe
1:39 PM GMT on July 11, 2015
One of my rules of thumb (acronym ROT from John Dutton, a PSU professor of mine)
is that severe weather season for the Mid Atlantic pretty much ends until September
as of July 10.

Well happy today! Frequency does drop off sharply about this time of year as we lose dynamics
and fronts start having trouble getting here as anything more than windshifts and 1C dewpoint drops. Second
season begins last week in August through October.

Yeah gross oversimplification esp.. this year when it looks like we'll still have westerlies but the rule holds a surprising fraction of summers
Member Since: December 31, 1969 Posts: Comments:
213. Xyrus2000
1:36 PM GMT on July 11, 2015
Quoting 201. yonzabam:

Earth heading for a mini ice age within 15 years

Incredible that this gets on to the front page of the UK Telegraph. The depths of scientific illiteracy are plumbed with the statement that solar output 'will decline by 60%'. Of course, this means that the oceans will freeze solid and all life on Earth will cease to exist. Still, in the short time we have left, we can stop fretting about global warming. Every cloud etc.

Link


Wow. And there are people who read garbage like that and actually believe it.

A 60% reduction in solar output wouldn't be a "mini-ice age". It would be a catastrophic extinction event not seen since the Permian-Triassic extinction that nearly wiped out all life on Earth. Even the tropics would freeze. Worse, a drop of that magnitude would also indicate the collapse of stellar fusion in the core. So it wouldn't be a mini anything. It would be the death knell for life as we know it on Earth.

But the author of that trash did get one thing right. We wouldn't have to worry about global warming anymore. :P
Member Since: December 31, 1969 Posts: Comments:
212. georgevandenberghe
1:35 PM GMT on July 11, 2015
Quoting 179. Xyrus2000:



Yep. The next Y2K will be in 2037 when the integer holding the number of milliseconds since 1/1/1970 flips over. You know, someone should really change that to a 64-bit long. It's on the TODO list, and that list is in the TODO basket which gets dumped into recycling every Tuesday.

More irritating is the compilers themselves. Fortran compilers are notorious for not reproducing exactly the same results using even the same code. The differences are usually very slight (distant decimal places), but it's enough to make model validation a real pain. Especially if said model exhibits non-deterministic/chaotic behavior. The whole butterfly flapping it's wings and all that. And you can't just "oh, that's close enough". Any deviation has to be explained since it could potentially be the result of a defect and not simply the compiler trying to be clever.

There are number of factors that can affect how the mathematical operations turn out. Except for bugs though, the differences are usually confined to the distant decimal places. There have been some notorious examples where that hasn't been the case (such as the Pentium division bug). That was a fun day for scientific computing.




Its seconds. Otherwise.. yep.

Most reproducibility issues come from nondeterministic ordering of calculations creating race conditions for when an operand is used. You are right also that this is scientifically okay in a weather model but makes validation of correctness of a change MUCH more difficult. So we insist on exact reproducibility. That makes debugging MUCH easier. The Intel compiler (NCEP uses Intel "Sandybridge" chips) has options that disable calculation reordering.. (-fp-model strict)
(that was the one with the POWER3/4/5/6/ xlf compiler also). The performance penalty using this is a few percent.

The MPI-1 (and followups) standard also encourages performance over reproducibiltity and reduction order in particular is likely to change from run to run. When users ask me how to fix this (besides getting on the standards committee) I tell them to either

1. Do reductions in quad precision and copy results to the precision of the rest of the model.
2. Normalize, do reductions in integer (guaranteed exact) and convert back to real and denormalize.
3. Write your own MPI reductions (that's easier than you think BTW)

Most users choose option 1. Fortunately with our implementation, reduction order is guaranteed if the decomposition doesn't change.
Member Since: December 31, 1969 Posts: Comments:
211. TCweatherman
1:27 PM GMT on July 11, 2015
Sorry I haven't been on latley, I've been very busy. Anyway hows it going?
Member Since: December 31, 1969 Posts: Comments:
210. HadesGodWyvern (Mod)
1:19 PM GMT on July 11, 2015
Japan Meteorological Agency
Tropical Cyclone Advisory #69
Typhoon Warning
TYPHOON NANGKA (1511)
21:00 PM JST July 11 2015
==========================
In Sea East Of The Philippines

At 12:00 PM UTC, Typhoon Nangka (950 hPa) located at 18.4N 139.0E has 10 minute sustained winds of 80 knots with gusts of 115 knots. The cyclone is reported as moving west slowly.

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

Gale Force Winds
=============
240 NM from the center in south quadrant
210 NM from the center in north quadrant

Dvorak Intensity: T5.0

Forecast and Intensity
==================
24 HRS: 18.9N 138.2E - 80 knots (CAT 3/Strong Typhoon) Sea East Of The Philippines
48 HRS: 21.2N 138.2E - 95 knots (CAT 4/Very Strong Typhoon) Sea South Of Japan
72 HRS: 24.4N 137.4E - 100 knots (CAT 4/Very Strong Typhoon) Sea South Of Japan

Japan Meteorological Agency
Tropical Cyclone Advisory #93
Typhoon Warning
TYPHOON CHAN-HOM (1509)
21:00 PM JST July 11 2015
==========================
about 170 KM Southeast Of Shanghai (China)

At 12:00 PM UTC, Typhoon Chan-Hom (965 hPa) located at 30.3N 122.8E has 10 minute sustained winds of 70 knots with gusts of 100 knots. The cyclone is reported as moving north at 9 knots.

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

Gale Force Winds
============
375 NM from the center in eastern quadrant
270 NM from the center in western quadrant

Dvorak Intensity: T4.5

Forecast and Intensity
==================
24 HRS: 36.0N 124.4E - 55 knots (CAT 2/Severe Tropical Storm) Yellow Sea
48 HRS: 39.6N 126.9E - Extratropical Low Overland Korean Peninsula
Member Since: December 31, 1969 Posts: Comments:
209. TimTheWxMan
1:06 PM GMT on July 11, 2015
2 enhanced risks in a row.... one on sunday and one on monday, though the latter's on my 21st birthday. Storms or beer? Everyone so far said storms lol.
Member Since: December 31, 1969 Posts: Comments:
208. Gearsts
1:02 PM GMT on July 11, 2015
Joe Bastardi ‏@BigJoeBastardi 1h1 hour ago
Euro with day 10 non tropical origin cyclone off east coast, typical tho of type of development this year

Eric Blake ‏@EricBlake12 13m13 minutes ago
@BigJoeBastardi the MDR of 2015 :)
Member Since: December 31, 1969 Posts: Comments:
207. toddbizz
12:49 PM GMT on July 11, 2015
Driest hottest summer I've ever seen in SE Florida.....wow it's hot and we get no relief from any cloud cover or spotty thunderstorms....El Nino related ?? Climate Change ?? Chinese Stock Market crash ?? who knows why ?? hopefully it'll rain soon....please bring it....
Member Since: December 31, 1969 Posts: Comments:
206. NativeSun
12:27 PM GMT on July 11, 2015
Quoting 162. Tazmanian:



guys nothing is going too happen any time soon in the Atlantic the Atlantic is closed sea tempers are not even 25C for the MDR and with high SAL and high wind shear your not going too see nothing turst me any wave that comes off will go poof my point is its not even worth look at the Atlantic this year has it is closed its not even worth looking at the Caribbean Sea thanks too vary high wind shear so the Caribbean Sea is all so closed this year the olny place if you want too track storms would be the gulf or off the E cost that would be the olny place too look this season


if you really want too track storms or want some in too track the W C and E PAC will be the place too track storms this season if you want too track monster storms
Quoting 174. whitewabit:



but aren't they getting more frequent and stronger ? But not in the Atlantic but in the Pacific theater ...
Member Since: December 31, 1969 Posts: Comments:
205. intampa
12:23 PM GMT on July 11, 2015
Quoting 194. StormTrackerScott:

GFS has a max of over 20" of rain off NE FL the next 2 weeks. May need to watch for another tropical system trying to form at the end of July of the SE Coast. Remember what I said earlier most if not all development will be close to the US this year.



something needs to happen. the heat and lack of rain here just east of tampa is frustrating and the plants are not liking it much either. seems we no longer have those "regular" afternoon showers that seemed to cover a lot more area like years past. its very scattered and usually I75 east. the spots that get it really get it but when its so hot and showers so scattered just doesnt seem like the rainy seasons of years past and thats been the way a few years now.
Member Since: December 31, 1969 Posts: Comments:
204. BahaHurican
12:17 PM GMT on July 11, 2015
Quoting 198. BahaHurican:


No need to guess what the wx will be like over Nassau today ... and I have PLANS ...
Just thought about this being the source of the system potentially forming later this month ....

The rain just started ...:-(
Member Since: December 31, 1969 Posts: Comments:
203. Tropicsweatherpr
12:16 PM GMT on July 11, 2015
TD at 8 AM PDT for system close to Mexican coast.


TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
500 AM PDT SAT JUL 11 2015

For the eastern North Pacific...east of 140 degrees west longitude:

1. An area of low pressure located about 1200 miles southwest of the
southern tip of Baja California Sur is moving north-northwestward at
about 10 mph. Shower and thunderstorm activity continues to show
signs of organization, and conditions are expected to be conducive
for the development of a tropical depression during tonight
or Sunday.
* Formation chance through 48 hours...high...90 percent
* Formation chance through 5 days...high...90 percent

2. Satellite images indicate that showers and thunderstorms associated
with a low pressure system located about 300 miles south-southeast
of Acapulco, Mexico have become better organized and a tropical
depression appears to be forming. If the current trend continues,
advisories will be initiated on this system later this morning.
Interests along the southern and southwestern coasts of Mexico
should monitor the progress of this disturbance.
* Formation chance through 48 hours...high...90 percent
* Formation chance through 5 days...high...90 percent

Forecaster Cangialosi
Member Since: December 31, 1969 Posts: Comments:
202. NativeSun
12:11 PM GMT on July 11, 2015
Quoting 87. 19N81W:


High pressure
It will be back in drought by the fall
Better question is why is the entire Caribbean basin white during our so called rainy season
I think we need to re write the climatology of our region it's been. Like this for the last couple years
Rain in May and June then not a drop till November for a bit then dry again till may or June
I have palm trees that are dying


A couple years, does not make a pattern change.
Member Since: December 31, 1969 Posts: Comments:
201. yonzabam
12:11 PM GMT on July 11, 2015
Earth heading for a mini ice age within 15 years

Incredible that this gets on to the front page of the UK Telegraph. The depths of scientific illiteracy are plumbed with the statement that solar output 'will decline by 60%'. Of course, this means that the oceans will freeze solid and all life on Earth will cease to exist. Still, in the short time we have left, we can stop fretting about global warming. Every cloud etc.

Link
Member Since: December 31, 1969 Posts: Comments:

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather