Abundant rain from the coastal low that was formerly Hurricane Ida is causing flooding in many locations in Southwest Virginia, including the Roanoke River. Click here for a Roanoke Times article on the flooding, and here for the National Weather Service in Blacksburg.
Going on leave for the next 2 weeks, I said I wouldn't get on the blog unless something extraordinary happens, and that appears to be on its way as Hurricane Ida defies a weak Atlantic tropical season and November norms and takes aim on the northern Gulf Coast. Hurricane warnings are out for portions of the Mississippi, Alabama and Florida Panhandle coasts. Ida will eventually be running over cooler water and into shearing winds aloft, but may have enough momentum to reach the Gulf Coast intact as a hurricane before becoming "extratropical." What happens to Ida's remnants afterward could be very important in Virginia's weather, as it has the potential to become an extratropical nore'easter type storm that could bring windy rain up and down the East Coast by mid-week ... or possibly only to parts of the Southeast, mostly staying to our south, if it is suppressed by a cold front advancing across the nation.
I will not be able to follow this closely the next few days, but you can on the following Web sites:
Hydrometoerological Prediction Center rainfall forecast maps
Tropical Storm Ida has formed in the Carribean near the Central American coast. It will likely soon move over Nicaragua and Guatemala, and though the National Hurricane Center is giving it some chance of regaining tropical storm strength later this week as it nears the Gulf of Mexico, there's a good chance it will rain itself out over the higher terrain of those countries. Late season tropical systems flooding the higher terrain of Central America can be very deadly, the extreme example being the 11,000-plus killed in 1998's Hurricane Mitch.
While Ida is unlikely to affect the U.S. as an organized tropical system, there's some chance its subtropical moisture could get pulled into the U.S. as new Pacific cold fronts and low-pressure systems move across in the next 7-10 days or so.
Atlantic hurricane season officially stretches until the end of November, but the 2009 season seems to be over with barely a whimper.
The most interesting event of the hurricane season on this blog was our discussion on Aug. 22 (and several days following) about proposals to use cold water upwelling to potentially weaken hurricanes. Reporter Duncan Adams wrote an extensive article about such a proposal from The Egg Factory of Roanoke, filed in 2000.
The discussion veered from whether such a thing was technically possible to more a philosophical question of whether man should even attempt such a thing. The critics of the plan generally said that man shouldn't tamper with nature and that doing so could produce unintended bad consequences. Supporters favored the hurricane-weakening proposals as a way to save lives and property damage along our coasts.
A few of you asked me to give some thoughts, which I have in the Weather Journal column that appears Friday in The Roanoke Times.
In the extended entry below (click "Read More" in full blog mode) is a short e-mail interview I had with George Hagerman, the Egg Factory's hurricane expert, about the group's proposal and its potential effects.
Feel free to weigh in again with your own comments, whether you have before or not -- just keep it civil.
Here's something you don't see everyday: An Atlantic tropical storm taking aim on Ireland. Tropical Storm Grace has formed in the far northeastern section of where you would expect any Atlantic tropical cyclone to form ... almost off the Atlantic map provided by the National Hurricane Center. Grace, a small tropical storm, peaked at 65 mph winds earlier today, but is still pretty potent with 60 mph winds. It is expected to become absorbed into a large extratropical low pressure system perhaps before it can make contact with the coast of Ireland.
In a recent discussion, the National Hurricane Center states: "IT IS WORTH NOTING THAT OTHER ATLANTIC TROPICAL STORMS HAVE FORMED FARTHER NORTH THAN GRACE DID. IN 2008 TROPICAL STORM LAURA WAS FIRST CLASSIFIED AS A TROPICAL STORM AT 40.6N....SLIGHTLY FARTHER NORTH THAN THE LATITUDE OF 40.2N WHERE GRACE WAS FIRST CLASSIFIED AS A TROPICAL STORM AT 0000 UTC TODAY. ALSO...IT IS LIKELY THAT POST-STORM ANALYSIS WILL SHOW GRACE BECOMING A TROPICAL STORM EARLIER...AND FARTHER SOUTH...THAN INDICATED OPERATIONALLY."
Meanwhile, there is another area in the central Atlantic that has a medium risk of becoming the next tropical storm, which would be named Henri. So though it has been an afterthought lately, Atlantic tropical season is continuing to kick along a bit.
An upper-level low slipping southeast from the Ohio Valley will likely trigger widespread showers and thunderstorms today, especially from the Roanoke Valley westward. The atmosphere is pretty thick with moisture, so locally heavy rain will be possible, as will gusty winds and some hail in the stronger storms, especially with a pool of cold air aloft that these storms may be able to bubble up into. The best chance of hail or high winds is over far Southwest Virginia no farther east than Wytheville, and not enough to rate a slight risk of severe weather (only a "See Text") by the Storm Prediction Center.
The coastal low is still there, though more offshore and weaker. Nonetheless, it is likely to affect our weather Thursday and Friday, as it meanders a bit back to the west, by pulling cooler air from the northeast into our area. Though the forecast for Thursday now is for highs in the 70s, it might not get out of the 60s if a thick bank of moisture, fog and clouds develops.
Speaking of the coastal low, David Sobotta, who goes back and forth between homes on a mountain overlooking the Roanoke Valley and the Crystal Coast of North Carolina (he has a local blog, View from the Mountain), measured 8.3 inches of rain on Labor Day from the coastal low. Here is a blog post he made about that.
The good news is that the National Hurricane Center no longer considers this low even a slight tropical development risk ... and distant Hurricane Fred is not going to get close to any significant land mass before sputtering out in the high-shear upper winds that are killing Atlantic tropical systems left and right this season.
Tropical Storm Fred has formed in the eastern Atlantic, but if it's track is close to what the National Hurricane Center is projecting, it won't get anywhere close to the any large land masses. Meanwhile, the hurricane center is still monitoring the storm off the Carolinas, but it appears unlikely to develop into a tropical storm because of strong winds aloft. Nonetheless, it will dump some heavy rains on the coast and might spit a little moisture back our way while it's at it.
Though the Atlantic tropical season has been underwhelming so far, there is a low-pressure system off the coast of the Carolinas that is being watched by the National Hurricane Center. However, it is given a low chance of development into a tropical system because upper-level winds remain too strong. So this probably won't become a tropical storm or hurricane. We'll be between this system and an upper-level low to the west, and thus there could be showers and some thunderstorms each day this week. National Weather Service radar has shown much of the rain overnight and this morning over West Virginia and the coalfields area of far Southwest Virginia.
A system in the eastern Atlantic just off the African coast is given a high chance of development by the hurricane center. It will likely become Tropical Storm Fred (and probably in time, Hurricane Fred -- unless the East Coast system somehow beats it to tropical development, which would push us down the list to Grace). It will be many days from any possible effects on the coast of the United States or any other North American or Caribbean nations.
What was once Tropical Storm Erika fizzled in the eastern Caribbean; its chances for a resurgence are considered very low. The National Hurricane Center is watching a new wave over the eastern Atlantic that might become Fred in a few days. But, while there are still several weeks of Atlantic tropical season to watch for possible development, it is obvious that this season so far is living up to El Nino-driven expectations that long-lived, strong tropical systems would be hard to come by in the Atlantic.
After a low of 51 in Roanoke and 48 in Blacksburg this morning -- indeed, the coolest since the first day of June -- very similar lows are expected tonight with clear skies, calm winds and low dew points. Thursday and Thursday night might be yet another repeat, with highs in the 70s and lows once again in the upper 40s to mid 50s. Looking farther out, a very long period of placid, normal to slightly cooler than normal weather appears in the offing, with highs on many days in the mid 70s to low 80s and lows in the mid 50s to low 60s.
Hurricane Erika could change that ... but it doesn't look like it will have a much of chance, between shearing winds aloft and running over land masses in the Caribbean. The National Hurricane Center forecasts Erika to drop off to a depression and then a remnant low approaching the Bahamas by Sunday.
Kevin Myatt works on the copy desk for The Roanoke Times and is its principal weather geek, writing a weekly weather column and advising the newsroom on weather topics. He helps guide students on a storm chasing trip to the central U.S. each May and was an editor for "Hurricanes and the Middle Atlantic States."
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