Latest on Tropical Storm Isaac

by Sean Morris
CNN Meteorologist

Isaac is forecast to make landfall in Hispaniola Friday evening as a category one hurricane and move over Port-au-Prince, Haiti, late Friday evening (EDT). Torrential rain of up to eight to twelve inches is possible over Hispaniola with maximum amounts of 20 inches possible. This will cause deadly flooding and mudslides. According to CNN International, 419,000 are still in living in tents in Port-au-Prince as a result of the 2010 quake.

The forecast track beyond this point is highly uncertain. According to the track, Isaac will approach and possibly make landfall along the Florida Keys on Monday. The official forecast track from the National Hurricane Center shows Isaac passing west of Tampa early Tuesday morning.

The forecast models are trending south and westward, away from Tampa.

(Based on 5 a.m. EDT Thursday 8/23 NHC Official Forecast Track)

  • Friday 2 p.m. EDT – Isaac is forecast to become a category one hurricane with winds of 75 mph on Friday afternoon.
  • Friday 6 p.m. EDT – Landfall in extreme southwestern Dominican Republic weakening to a strong tropical storm shortly thereafter.
  • Friday 8 p.m. EDT to midnight – Moves over Port-au-Prince, Haiti, with maximum sustained winds at about 65 mph.

NOTE LARGE ERRORS are possible in the forecast track for times below:

  • Saturday evening/overnight – landfall in southeastern Cuba
  • Sunday afternoon – Isaac emerges into the Florida Straits, begins intensifying

 NOTE VERY LARGE ERRORS are possible in the forecast track for times below (at least 250 miles either side of the forecast track):

  • Overnight Sunday – possible landfall in Florida Keys as a category 1 hurricane, winds 75 mph or greater
  • Early Tuesday – Isaac passes west of Tampa
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Could Hurricane Isaac threaten the Republican Convention?

by Dave Hennen
CNN Senior Meteorologist

A hurricane hitting Tampa during the Republican Convention?   It’s the talk around the CNN Newsroom, in editorial and planning calls, and certainly the talk around the Weather Center this afternoon.

What are the odds?  Convention planning has been going on for more than a year.  It’s like booking that vacation in the Caribbean during hurricane season.   I tell people all the time who ask me “should I take that August cruise,” go for it!  There is a chance, but even during the season a storm hitting a particular location on a map are minuscule, even at the height of hurricane season.    Dr. Jeff Masters, a respected meteorologist with the website, previously calculated that based on climatology there was a 2-in-one-thousand chance that a hurricane would hit Tampa during the convention.  The odds are higher today, as Tropical Storm Issac churns towards the Caribbean and likely heads in the general direction of Florida.

Some of the fastest computers in the world crunch this data and spit out the likely path and strength of the storm based on a number of conditions. The world of thermo and fluid dynamics and the movement of invisible air is not for the faint of heart. Think of throwing a stick in a stream and trying to figure out where it will be in 3 days.

What we see on the other side of these billions of calculations are the computer model plots, also known as the familiar “spaghetti plots”

Each line represents a different model’s interpretation of what is going to happen.  It’s kind of like giving an MRI or X-ray image to 10 doctors and adding on other things like vital signs, temperature, etc.   You may get 10 different diagnoses of what is ailing you.  That same is true of the computer model plots, and like doctors, some are more reliable than others.  The problem is, some of our best model “doctors” take Isaac into the Gulf of Mexico, which would make a landfall somewhere in the U.S. more likely.

What is interesting about forecasting is that in the short term our forecasts have become  pretty good.   The average error on a 12 hour forecast from the National Hurricane Center is only 36 miles, but the problem is any potential impacts to Tampa, or anywhere in the U.S., are probably at least 5 to 7 days away.  The average error that far out is over well over 250 miles.   So while odds are higher than the Republican Convention planners would like them to be, were not raising the red flag yet for Tampa.  My advice for all heading to, or living in Tampa, as well as anyone along the Gulf or East Coast, is keep a close eye on Isaac.  It could turn into a destructive storm.


CNN International Senior Meteorologist Brandon Miller contributed to this report.

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New Tropical Depression in the Atlantic

by Dave Hennen
CNN Senior Meteorologist

As we head towards the peak of hurricane season in early September the tropics continue to be active.   Tropical Depression Nine has formed in the central Atlantic, and is forecast to strengthen into a Tropical Storm later on today.  The system is currently located over 500 miles east of the Leeward and Windward Islands with maximum sustained  winds of 35 mph. The storm is forecast to become a tropical storm later today, and could reach hurricane intensity as it moves into the Caribbean. Tropical Storm watches and warnings cover much of the Leeward Islands as well as Puerto Rico and the Virgin Islands.    It is still too early to tell what if any effects this could have on the U.S. mainland, but there are several computer models that bring the storm into the Gulf of Mexico, while others move the storm further east.  With roughly 50,000 people headed for Tampa for the Republican National Convention on August 27-30th there is heightened interest in the future path of the storm.

Were also watching another disturbance even further east that is located roughly 400 miles southwest of the Cape Verde Islands that the National Hurricane Center is saying has a 60% chance of becoming a named storm in the next 48 hours. 


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Mars rover Curiosity beams back new data and images

by Sean Morris
CNN Meteorologist

During a NASA teleconference on Friday afternoon NASA scientists revealed new data and images from the surface of Mars that were captured by Curiosity.

Weather data was beamed back to Earth on Friday for the first diurnal cycle of Curiosity’s location. Readings showed the high temperature during the cycle was only 1 degree Celsius. The weather data comes from the Spanish-built Rover Environmental Monitoring Station (REMS). The instrument will run for approximately five minutes every hour night and day. The REMS will record wind speed and direction, temperature and humidity. Other sensors will monitor radiation on the planet’s surface.

The is the first time in 30 years that there is a continuously operating weather station on the surface of Mars. The last time weather readings were beamed back to Earth from the surface was in 1982 from the Viking lander.

Image 1. The following image (cut out from a mosaic of images) shows the view from the landing site of Curiosity toward the lower reaches of Mount Sharp. Curiosity is expected to begin its ascent through hundreds of feet of layered deposits here. The lower several hundred feet show evidence of containing hydrated minerals based on Mars Reconnaissance Orbiter (MRO) observations. The terrain is similar to the four-corners region of the United States.

Image 2. The image below is a self-portrait of the rover Curiosity from its Navigation camera. This composite image was composed from a mosaic of 20 images.

Images 3a/3b. The following images show four blast marks from Curiosity’s descent stage rockets. The rockets blew away some of the material on the surface. The blast marks were named from a list of rock formations in Canada. They all have something to do with heat. This image was taken from the rover’s mast camera.

Image 4: The image below is a close up of one of the four blast marks created on the surface of Mars from the rover’s descent stage rockets. This blast mark is located near the left wheel of the rover. The scour mark is named after a 2-billion-year-old sequence of rocks in northern Canada.

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Heat returns to the West

by Sean Morris
CNN Meteorologist

The upper-level area of high pressure, referred to as a high pressure “ridge,” that has dominated the weather pattern over much of the Midwest this summer is shifting westward this week. This means cooler, wetter conditions for areas suffering from the record drought that is plaguing most of the Great Plains and Midwest with hot, dry conditions west of the Rockies.

As the ridge shifts westward, hot, dry conditions will also spread toward the Pacific Coast. Easterly winds will push cooler air offshore in the Pacific Northwest later this week. The cooler air will be replaced by hot, dry air across coastal sections of Washington and Oregon. Portland will see high temperatures in the upper 90s and even pushing past the century mark in some areas of western Oregon by the end of the week. Seattle will see high temperatures in the lower 90s which is about ten to 15 degrees above normal afternoon highs in late August. Fortunately, the heat will not last long, and cooler conditions are expected to move into Oregon and Washington by the weekend.

The return of hot, dry air across the West Coast will not help firefighters battling blazes across the area that erupted on Monday afternoon. Red Flag Warnings are now in effect for much of Montana, areas of Idaho and much of Wyoming. Winds are expected to be light across the area, which is good news for crews trying to contain the blazes.

Extreme heat is in the forecast for the Desert Southwest. The scorching temperatures have prompted Excessive Heat Warnings in southern California and southwestern Arizona. High temperatures are expected to push upwards to 110 degrees in Phoenix on Wednesday, with high temperatures continuing to push above the century mark well into the weekend.

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Tropics Staying Alive

by Sarah Dillingham
CNN Meteorologist

After Hurricane Ernesto made landfall along the eastern coast of the Yucatan Peninsula late last Wednesday, August 8, all weather eyes switched back to the tropics.  Conditions had remained quiet since mid-June when TS Debby’s drought-busting rains wreaked havoc across Florida, dropping over two feet of rain across northern portions of the state.  Tropical Storm Florence was a brief development last week, but fizzled rather quickly after becoming the Atlantic Hurricane season’s 6th named storm of 2012.  Tropical Depression 7 had its own quick run late last week, which had decent hopes of become Gordon, but failed to develop as its path over cooler waters proved to be too much for it to survive.

The National Hurricane Center is still monitoring the remnants of TD-7 as it enters the Caribbean, giving it a 10%, or low chance of development the next 48 hours.  Another wave located about 1200 miles west-northwest of the Cape Verde Islands also has a 10% chance of development, but even if this wave does develop in the coming days, early forecast models predict it to sharply recurve into the open waters of the Atlantic.

The Eastern Pacific has come alive in recent days with the development of Tropical Storm Hector off the western coast of Mexico, and another wave just south of Acapulco has been given a 20% chance of development over the next 48 hours.  TS Hector developed partially out of the remnants of Hurricane Ernesto, although not part of the original surface circulation, according to National Hurricane Center Specialist John Cangialosi.  He said, “The remnants of the surface circulation of Ernesto dissipated over the mountains of Mexico.  There was an upper-level circulation center associated with Ernesto that interacted with a separate system that went on to spawn Hector in the Pacific Basin.”

Over the next several days, forecasters will be monitoring the waves in the Atlantic and Pacific Basins for further development, and with the updated release of the 2012 Atlantic Hurricane Season forecast by NOAA, everyone will surely be paying attention to see how busy the season will get.

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Supercell Causes Heavy Damage to Oklahoma Community

by Sarah Dillingham
CNN Meteorologist

Severe storms rattled through the Southern Plains Sunday afternoon, causing heavy damage to at least one Oklahoma town in Bryan County.  Calera, OK saw numerous downed trees and powerlines, including structural damage to several homes.  One mobile home was overturned along a highway, leaving it a total loss, and roof damage was also being reported by some residents.  There were no official reports of tornadoes yesterday, according to the Storm Prediction Center, but several reports of high winds up to 60 and 70 mph were reported in the nearby towns of Kemp and Achille in Bryan County, OK.

Strong straight-line winds were the likely culprit of this intense storm, but the National Weather Service will head out to the town today and determine if that was the case.  These storms formed along a cold front that has brought some much needed cooler weather to the Great Lakes and Northeast over the weekend, and even Oklahoma is seeing some relief from the extreme heat.  As this front continues sliding to the southeast today, more severe storms are expected across western Tennessee, Kentucky, and Mississippi where large hail, damaging winds, and isolated tornadoes will be possible.  Please stay aware of developing weather conditions in your area, and seek shelter for any impending severe weather.

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