Red River rising: 18th consecutive year of flooding--why?

By: Dr. Jeff Masters , 3:08 PM GMT on March 19, 2010

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The Red River at Fargo, North Dakota continues to rise, with a peak expected Sunday at the 4th highest flood level observed in the past century. "Major" flood level is 30 feet, which the river surpassed on Wednesday, and the river is expected to crest near 38 feet on Sunday, just 2.8 feet below the record set last year. Flood stage is eighteen feet, and the Red River has now reached flood stage at Fargo for eighteen consecutive years, according to the U.S. Army Corps of Engineers. Prior to this remarkable stretch of flooding (which began in 1993), the river flooded in just 29 of 90 years. This year's flood is rated as somewhere between a 50-year and 100-year flood. Last year's record flood was a 100-year flood. The U.S. Army Corps of Engineers lists the 10-year flood level for the Red River at Fargo to be 10,300 cubic feet per second. A 10-year flood, historically, has a 10% chance of occurring in a given year. In the last twenty years, the Red River has had eight 10-year floods--one every 2.5 years, on average. This year is the fourth year out of the past five with a 10-year flood. Clearly, flooding has increased significantly along the Red River over the past twenty years.


Figure 1. Current and forecast flood stage for the Red River of the North at Fargo, ND. You can access images like these using our wundermap for Fargo with the "USGS River" layer turned on. Click on the icon for USGS station 05054000, then hit the "click for graph" link.

Reasons for flooding: landform factors
According the U.S. Geological Survey, the unique landform characteristics of the Red River Valley make it highly susceptible to flooding. These factors include:

1) A relatively shallow and meandering river channel--a shallow channel holds less water and the meandering can cause flow to slow down as the channel makes its turns, causing over-bank flooding.

2) A gentle slope (averaging 0.5 to 1.5 feet per mile) that inhibits channel flow and encourages overland flooding or water "ponding" (especially on even, saturated ground) in the basin.

3) The northerly direction of flow--flow in the Red River travels from south (upstream) to north (downstream). The direction of flow becomes a critical factor in the spring when the southern (upstream) part of the Red River has thawed and the northern (downstream) part of the channel is still frozen. As water moves north toward the still frozen river channel, ice jams and substantial backwater flow and flooding can occur.


Figure 2. Peak flow of the Red River at Fargo, North Dakota through time. The two largest flow rates occurred last year (2009), and in 1997. The projected crest for Sunday (red circle) would be fourth greatest flood since reliable records began in 1901. Image credit: U.S. Geological Survey.

Reasons for this year's flood: highly unfavorable weather conditions
The USGS also cites five weather factors that can act to enhance flooding along the Red River. All five of these factors occurred to a significant degree this year:

1) Above-normal amounts of precipitation in the fall of the year that produce high levels of soil moisture, particularly in flat surface areas, in the basin. North Dakota had its 22nd wettest fall in the 115-year record in 2009.

2) Freezing of saturated ground in late fall or early winter, before significant snowfall occurs, that produces a hard, deep frost that limits infiltration of runoff during snowmelt. Fargo had a November that was much warmer than average, followed by a sudden plunge to below-zero temperatures by the second week of December. This froze the saturated ground to a great depth.

3) Above-normal winter snowfall in the basin. North Dakota had a top 15% winter for precipitation, with the period December 2009 - February 2010 ranking 15th wettest in the past 115 years.

4) Above-normal precipitation during snowmelt. Precipitation for March 1 - 18 has been 1.41", compared to the average of 0.61".

5) Above-normal temperatures during snowmelt. High temperatures in Fargo have averaged 6°F warmer than normal for March 1 - 18.

Urbanization increases flooding
Urbanization has had a major impact on increasing flooding not only along the Red River, but in every river basin in the U.S. Many cities and developed areas are located in flood plains next to major rivers and their tributaries. Highways, streets, parking lots, sidewalks, and buildings now cover large areas of the ground that used to absorb excess rain water and slow the rate at which run-off from precipitation and melting snow reached rivers. By developing large portions of our flood plains, run-off now reaches rivers more quickly, generating higher floods.

Building levees and flood defenses increases flood peaks
Defending ourselves against floods has made floods worse. Every time a new levee is built, or an old floodwall raised in height to prevent overtopping, more and more water is forced into the river bed, which raises the height of the flood. Flood waters that used to be able to spread out over their natural flood plains are now forbidden from spilling out over newly developed land in flood plains. For example, proposed improvements to the flood defense system in Fargo could cause a 4 - 10 inch rise in floods immediately downstream from the city, according to the Army Corps of Engineers.

Precipitation is increasing
As the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 IPCC report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. Satellite measurements (Trenberth et al., 2005) have shown a 1.3% per decade increase in water vapor over the global oceans since 1988. Santer et al. (2007) used a climate model to study the relative contribution of natural and human-caused effects on increasing water vapor, and concluded that this increase was "primarily due to human-caused increases in greenhouse gases". This was also the conclusion of Willet et al. (2007). This increase in water vapor has very likely led to an increase in global precipitation. For instance, over the U.S., where we have very good precipitation records, annual average precipitation has increased 7% over the past century (Groisman et al., 2004). Precipitation over the Red River drainage basin increased by about 10 - 20% during the 20th Century (Figure 3.) The same study also found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events over the U.S. in the past century. These are the type of events most likely to cause flooding. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then.


Figure 3. Change in precipitation over the U.S. between 1900 - 2000, from the U.S. Cooperative network. Precipitation in the Red River drainage area increased by 10 - 20% over the 20th century. Image credit: Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends (Groisman et al., 2002).

The future of flooding
As the population continues to expand, development in flood plains and construction of new levees and flood protection systems will continue to push floods to higher heights. With global warming expected to continue and drive ever higher precipitation amounts--falling preferentially in heavy precipitation events--it is highly probable that flooding in the Red River Valley--and over most of the northern 2/3 of the U.S. where precipitation increases are likely--will see higher and more frequent floods. With these higher and more frequent floods comes the increased risk of multi-billion dollar disasters, when a record flood event overwhelms flood defenses and inundates huge areas of developed flood plains. Obviously, we need to make smart decisions to limit development in flood plains to reduce the cost and suffering of these future flooding disasters.

References
Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895.2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64.85.

Milly, P.C.D., R.T. Wetherald, K.A. Dunne, and T.L.Delworth, Increasing risk of great floods in a changing climate", Nature 415, 514-517 (31 January 2002) | doi:10.1038/415514a.

Santer, B.D., C. Mears, F. J. Wentz, K. E. Taylor, P. J. Gleckler, T. M. L. Wigley, T. P. Barnett, J. S. Boyle, W. Brüggemann, N. P. Gillett, S. A. Klein, G. A. Meehl, T. Nozawa, D. W. Pierce, P. A. Stott, W. M. Washington, and M. F. Wehner, 2007, "Identification of human-induced changes in atmospheric moisture content", PNAS 2007 104: 15248-15253.

Trenberth, K.E., J. Fasullo, and L. Smith, 2005: "Trends and variability in column-integrated atmospheric water vapor", Climate Dynamics 24, 741-758.

Willett, K.M., N.P. Gillett, P.D. Jones, and P.W. Thorne, 2007, "Attribution of observed surface humidity changes to human influence", Nature 449, 710-712 (11 October 2007) | doi:10.1038/nature06207.

Links
A good way to track the flooding event is to use our wundermap for the Red River with the USGS River layer turned on.

The Fargo Flood webpage of North Dakota State University, Fargo, has some excellent links.

I'll have a new post on Monday or Tuesday.

Jeff Masters

Red River Flood 2006 (mw25)
The water level of the Red River when I took this photo was 47.2 feet, 19.2 feet above flood stage and the 6th highest level in Grand Forks' history. The river is expected to crest at 47.4 feet on Wednesday morning. Luckily, no homes have been lost in the Grand Forks area as of yet due to the flooding.
Red River Flood 2006
Fargo Flood 2009 - Elm & 15th Ave. N. (tliebenow)
Picture says it all. Clay dike built to contain the Red River in North Fargo.
Fargo Flood 2009 - Elm & 15th Ave. N.

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661. xcool
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The Caribbean certainly looks to be a hot spot this year and the rest of the MDR for that matter.
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting Levi32:
It should also be noted that drier conditions in the eastern Atlantic this winter have resulted in less low-level cloudiness than normal, which has contributed to allowing the SSTs to warm up so much.
yep but as we approach the start of the season that will change with more cloudiness and northward moving ITCZ's and eastly waves lots of cloudiness will come hopefully check those sst's and cool them a little
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Quoting hurricane23:


Which also might aide a few tc's staying out to sea.


Hopefully, although if the models are right we will see the pool of warmest SST anomalies shift westward into the Caribbean by the height of the season.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
657. xcool
now down to 72 days
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Quoting Drakoen:
Those anomalously higher SSTs should lead to the early formation of tropical wave in the eastern Atlantic. In the past few seasons we would typically wait until waves reach around 50W to reach the 26C isotherm. By that time waves usually lose there amplitude. This season will likely not see that same fate.


Which also might aide a few tc's staying out to sea.
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Why's there a cold spot south of the tip of Cuba?
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Quoting Drakoen:
Those anomalously higher SSTs should lead to the early formation of tropical wave in the eastern Atlantic. In the past few seasons we would typically wait until waves reach around 50W to reach the 26C isotherm. By that time waves usually lose there amplitude. This season will likely not see that same fate.


Indeed. We could see a Bertha-like storm try to develop in July.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Those anomalously higher SSTs should lead to the early formation of tropical waves in the eastern Atlantic. In the past few seasons we would typically wait until waves reach around 50W to reach the 26C isotherm. By that time waves usually lose their amplitude. This season will likely not see that same fate.
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting Hurricanes101:


but isnt it true in the MDR that its not really the SSTs that prohibit development out there this time of year, that it is more the upper level patter and wind shear?


Yes, that is why we rarely see any storms form east of 70W during the early months of the hurricane season. Even though we have record SSTs in the eastern Atlantic, it is highly unlikely that we will see a storm form way out there during May or June. It almost never happens. The ITCZ isn't far enough north in May and June anyway.
Member Since: November 24, 2005 Posts: 635 Comments: 26661

2010:


2005:
Member Since: June 9, 2007 Posts: 4 Comments: 15921
Quoting Levi32:


We're now pushing areas of 3C+ above normal in the eastern Atlantic:



but isnt it true in the MDR that its not really the SSTs that prohibit development out there this time of year, that it is more the upper level patter and wind shear?
Member Since: March 10, 2010 Posts: 1 Comments: 7831
Quoting Drakoen:
Extremely impressed with our Sea-Surface Temperatures:



We're now pushing areas of 3C above normal in the eastern Atlantic around the Cape Verde Islands:

Member Since: November 24, 2005 Posts: 635 Comments: 26661
Extremely impressed with our Sea-Surface Temperatures:

Member Since: October 28, 2006 Posts: 57 Comments: 30577
647. Skyepony (Mod)
winter123~ we had a minute of rotation around Haiti yesterday, a special feature in the afternoon tropical discussion. Also many times those earlier SW Caribbean storms begin from a tropical wave + a tail of a front.

Hades~ Ului has acted like more than just land friction tighting a little on landfall. They did say they were overly saturated before this hit. Wonder if it came in over some shallow hot standing water.
Member Since: August 10, 2005 Posts: 179 Comments: 38326
It should also be noted that drier conditions in the eastern Atlantic this winter have resulted in less low-level cloudiness than normal, which has contributed to allowing the SSTs to warm up so much.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
645. xcool
WE "GET CLOSE to hurricane season yayy
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Quoting winter123:


Thanks. So I understand now that you were saying a strong African wave so early in the season has possible implications for later in the season. But I also saw that there is an insane amount of dust, as there has been the past few years... Any chance of that letting up?



I believe those were all subtropical->tropical storms. But if someone wants to prove me wrong, like maybe a SW Caribbean storm that formed in feb-march-april?


Back to this thing... and with what I said above in mind. Is it a good sign that the carribean is moist right now? Or is it pretty common? It actually looks like rotation in the carribean, but I'm guessing that's just the contours of the land?

Link


Well it has been a bit drier than normal in the eastern tropical Atlantic all winter long, courtesy of El Nino, but those conditions should turn around and become opposite to what they are now as El Nino dies and becomes neutral.

Also, a lot of that dust is coming from areas that typically see nearly no rain during the winter months. The Sahel region of western Africa doesn't start seeing significant precipitation until May or June when the ITCZ starts to move substantially northward. When that happens we will be monitoring rainfall anomalies in the Sahel region, which can tell us whether dust may be above or below normal this summer (more rain = less dust).

The rotation in the western Caribbean that you are seeing is likely due to a disturbance along an old front that has stalled down in that area. There have been a few disturbances along that boundary over the last couple days, bringing some rain to Hispaniola.

700mb Specific Humidity January 1st to March 18th:
Member Since: November 24, 2005 Posts: 635 Comments: 26661
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642. HadesGodWyvern (Mod)
Tropical Cyclone Warning Center Brisbane
Tropical Cyclone Warning
Tropical Cyclone Ului, CAT 2
5:00 AM EST March 21 2010
=====================================

At 18:00 PM UTC, Tropical Cyclone Ului, Category 3 (975 hPa) located at 20.4S 148.4E or 40 kms south southeast of Bowen and 120 kms northwest of Mackay has 10 minute sustained winds of 60 knots with gusts of 85 knots. The cyclone is reported as moving west southwest at 12 knots.

Ului crossed the coast near Airlie Beach at 1.30am. The centre of the cyclone is currently moving inland near Collinsville. The cyclone is expected to rapidly weaken as it moves further inland this morning.

DESTRUCTIVE wind gusts to 155 km/hr are expected to continue affecting the coastal and island communities between Bowen and Seaforth for the next hour or two.

DAMAGING winds are expected in areas between Ayr and Sarina over the next few hours, and extending to adjacent inland parts during the morning.

Winds will continue to ease during the day.

HEAVY RAINFALL and flooding are likely to continue about coastal and adjacent inland areas between Bowen and St Lawrence.

DANGEROUS SURF conditions are expected to continue about exposed beaches south of the cyclone until later today. A separate Severe Weather Warning is current for these conditions.

People in the path of the cyclone should stay calm and remain in a secure shelter while the destructive winds continue over the next few hours.

Do not venture outside if you find yourself in the eye of the cyclone as winds may remain light for up to an hour - very destructive winds from a different direction could resume at any time. Heed the advice and follow the instructions of Police or State Emergency Service personnel.

Dvorak Intensity: T4.0/4.0/D0.5/24hrs

Storm Force Winds
==================
20 NM from the center in northern quadrant
50 NM from the center in southeast quadrant
40 NM from the center in southwest quadrant

Gale Force Winds
================
120 NM from the center in southwestern quadrant
140 NM from the center in southeastern quadrant
90 NM from the center in northeastern quadrant
120 NM from the center in northwestern quadrant

Forecast and Intensity
=======================
12 HRS: 21.0S 146.2E - 30 knots (Tropical Low)
24 HRS: 20.6S 143.6E - 25 knots (Tropical Low)
48 HRS: 18.3S 137.3E - 20 knots (Tropical Low)
72 HRS: 17.4S 130.7E - 20 knots (Tropical Low)

Tropical Cyclone Watches
===========================
A Cyclone WARNING continues for coastal areas from Ayr to Sarina and adjacent inland areas, including Charters Towers and Moranbah.

The Cyclone WARNING from Townsville to Ayr and from Sarina to St Lawrence has been CANCELLED.

Additional Information
==========================
Tropical Cyclone Ului is currently overland and weakening. Dvorak analysis: DT=4.0. Current intensity based on observations. The cyclone is expected to weaken as it moves inland during Sunday.
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Quoting Levi32:



Nobody said anything about it developing lol. We're excited that it might be a significant feature this early in the year. It is intriguing and out of the ordinary. We're not even thinking about tropical development. The first tropical wave of the year never develops.


kinda like the first batch of cookies!

afternoon everyone
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Quoting Levi32:


That image shows total precipitable water (essentially the water vapor content of the atmosphere, how moist it is). Orange and red colors represent areas of deep, high moisture content, which is a favorable environment for tropical cyclones to develop in.


Thanks. So I understand now that you were saying a strong African wave so early in the season has possible implications for later in the season. But I also saw that there is an insane amount of dust, as there has been the past few years... Any chance of that letting up?

Quoting wunderkidcayman:


may I remind you guys that we had have storms in March and Febuary


I believe those were all subtropical->tropical storms. But if someone wants to prove me wrong, like maybe a SW Caribbean storm that formed in feb-march-april?


Back to this thing... and with what I said above in mind. Is it a good sign that the carribean is moist right now? Or is it pretty common? It actually looks like rotation in the carribean, but I'm guessing that's just the contours of the land?

Link
Member Since: July 29, 2006 Posts: 28 Comments: 1799
Quoting winter123:
Wow, this is really cool imagery. So basically the dark red-ish is where it's favorable wind-wise for cyclones to form? You can see Ului and 98W to it's north, which is looking really good. Lots of convergence causing it to spin.


Link


That image shows total precipitable water (essentially the water vapor content of the atmosphere, how moist it is). Orange and red colors represent areas of deep, high moisture content, which is a favorable environment for tropical cyclones to develop in.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Quoting winter123:


Can't believe people are seriously discussing a blob on the ITCZ for development. Did you forget, it's MARCH?


may I remind you guys that we had have storms in March and Febuary
Member Since: June 13, 2009 Posts: 2 Comments: 12180
Quoting winter123:


Can't believe people are seriously discussing a blob on the ITCZ for development. Did you forget, it's MARCH?

Quoting winter123:


Not sure why people are talking about it so in-depth if they don't want it to develop. I guess they are just that bored. Even though we have a landfalling cyclone right now. Anyway, look at the last frame, it's about to be sheared to bits in the next 12-24 hours.


Nobody said anything about it developing lol. We're excited that it might be a significant feature this early in the year. It is intriguing and out of the ordinary. We're not even thinking about tropical development. The first tropical wave of the year never develops.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Wow, this is really cool imagery. So basically the dark red-ish is where it's favorable wind-wise for cyclones to form? You can see Ului and 98W to it's north, which is looking really good. Lots of convergence causing it to spin.


Link
Member Since: July 29, 2006 Posts: 28 Comments: 1799
Quoting Hurricanes101:


who said anything about it developing?

Did I miss something?


Not sure why people are talking about it so in-depth if they don't want it to develop. I guess they are just that bored. Even though we have a landfalling cyclone right now. Anyway, look at the last frame, it's about to be sheared to bits in the next 12-24 hours.
Member Since: July 29, 2006 Posts: 28 Comments: 1799
634. Skyepony (Mod)
If it pulls off persistence I think we've got our first tropical wave. It is a surface trough & certainly born of the ITCZ.

Tropical waves, or easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of cloudiness and thunderstorms. West-moving waves can also form from the tail end of frontal zones in the subtropics and tropics and may be referred to as easterly waves, but these waves are not properly called tropical waves; they are a form of inverted trough sharing many characteristics with fully tropical waves. All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeast Pacific basins
Member Since: August 10, 2005 Posts: 179 Comments: 38326
Quoting winter123:


Can't believe people are seriously discussing a blob on the ITCZ for development. Did you forget, it's MARCH?


who said anything about it developing?

Did I miss something?
Member Since: March 10, 2010 Posts: 1 Comments: 7831
Quoting cchsweatherman:
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 5N23W 4N25W CROSSING THE
EQUATOR NEAR 43W AND INTO NE BRAZIL NEAR 1S47W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE FROM THE EQUATOR TO 7N
E OF 07W. A SURFACE TROUGH IS EMBEDDED WITHIN THE AXIS FROM
2N-8N ALONG 24W.
SCATTERED MODERATE CONVECTION IS FROM 2N-8N
BETWEEN 19W-28W. THE CONVECTION ASSOCIATED WITH THE SURFACE
TROUGH CONTINUES TO BE ENHANCED EAST OF AN UPPER LEVEL LOW
CENTERED OVER THE TROPICAL ATLC NEAR 6N34W.


Can't believe people are seriously discussing a blob on the ITCZ for development. Did you forget, it's MARCH?
Member Since: July 29, 2006 Posts: 28 Comments: 1799
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N11W 5N23W 4N25W CROSSING THE
EQUATOR NEAR 43W AND INTO NE BRAZIL NEAR 1S47W. CLUSTERS OF
SCATTERED MODERATE/STRONG CONVECTION ARE FROM THE EQUATOR TO 7N
E OF 07W. A SURFACE TROUGH IS EMBEDDED WITHIN THE AXIS FROM
2N-8N ALONG 24W.
SCATTERED MODERATE CONVECTION IS FROM 2N-8N
BETWEEN 19W-28W. THE CONVECTION ASSOCIATED WITH THE SURFACE
TROUGH CONTINUES TO BE ENHANCED EAST OF AN UPPER LEVEL LOW
CENTERED OVER THE TROPICAL ATLC NEAR 6N34W.
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Member Since: June 9, 2007 Posts: 4 Comments: 15921
Quoting StormW:
Definitely got some dust comin' out



You can see the dry air coming off, as well as a bulge in the ITCZ associated with the trough, in the North Atlantic TPW animation.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Quoting beell:


Opinions are what we do here lol. Basing mine on the 12Z 650mb analysis you posted earlier.


That's what I was looking at as well lol.



Member Since: November 24, 2005 Posts: 635 Comments: 26661
Current SAL Analysis,Atlantic
Member Since: July 3, 2005 Posts: 426 Comments: 128874
624. beell
Quoting Levi32:


Well, the axis is all the way up to 10N south of the Cape Verde Islands, and the jet core over western Africa has wind speeds of 3-5 m/s above normal for this time of year. The overall jet axis is at 5N-6N when the mean position for March is closer to 2N. I dunno, just my opinion as well, lol.


Opinions are what we do here lol. Basing mine on the 12Z 650mb analysis you posted earlier.
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Quoting Tropicsweatherpr:
Invest 98W is still with a broad circulation.Will it organize into something more stronger?

Link


TROPICAL DISTURBANCE SUMMARY:

(1) THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 3.0N

155.1E, IS NOW LOCATED NEAR 3.9N 148.5E, APPROXIMATELY 295 NM

SOUTHWEST OF CHUUK. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY

SHOWS A DISTINCT YET BROAD AREA OF CYCLONIC TURNING WITH SPOTTY DEEP

CONVECTION FLANKING THE OUTER PERIPHERY. A 200345Z AMSU-B MICROWAVE

IMAGE SHOWS WEAK AND LIMITED BANDING STRUGGLING TO WRAP INTO THE LOW

LEVEL CIRCULATION CENTER (LLCC). A PARTIAL 191118Z ASCAT PASS DOES

NOT REVEAL A LLCC, BUT RATHER PRONOUNCED TROUGHING WITH STRONG

CONVERGENT FLOW WITHIN THE WESTERN HALF. THE UPPER LEVEL ENVIRONMENT

HAS DEGRADED SOMEWHAT WITH THE NORTHWARD MIGRATION OF THE RIDGE AXIS

OVER THE PAST 12 HOURS. VERTICAL WIND SHEAR HAS ELEVATED IN

RESPONSE. FAVORABLE DIFFLUENCE ALOFT PERSISTS NONETHELESS. MAXIMUM

SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA

LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR

THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24

HOURS REMAINS FAIR.
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Invest 98W is still with a broad circulation.Will it organize into something more stronger?

Link
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Quoting beell:
Thanks,
Looks "normal" to me. Just an opinion of course.


Well, the axis is all the way up to 10N south of the Cape Verde Islands, and the jet core over western Africa has wind speeds of 3-5 m/s above normal for this time of year. The overall jet axis is at 5N-6N when the mean position for March is closer to 2N. I dunno, just my opinion as well, lol.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
620. beell
Thanks.
Looks "normal" to me. Just an opinion of course.
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Africa and eastern Atlantic Visible/IR Loop (images every hour)
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Magnitude 5.6 - CUBA REGION
2010 March 20 18:08:10 UTC
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The 850mb vorticity with the feature isn't that impressive:

Member Since: November 24, 2005 Posts: 635 Comments: 26661
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Quoting beell:
You got one for April, Levi?


4N-5N

Member Since: November 24, 2005 Posts: 635 Comments: 26661
Quoting StormW:
Quoting wunderkidcayman:


so surface trough or tropical wave


We'll see which one the NHC calls it at 18z.



Turn this upside down...what do you have?



Right...tropical waves are inverted troughs. That's why having an inverted surface trough moving westward over the eastern Atlantic is only one small step away from a tropical wave. It doesn't really have a great surface signature, so I'm fine with it not being called a TW. The AEJ is impressive though for this time of year right now.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
612. beell
You got one for April, Levi?
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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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