Typical late August weather in SW Virginia as we watch Isaac’s likely path shift west into Gulf of Mexico
Roanoke and Blacksburg were exactly 1 degree below normal for both high and low on Thursday (84/63 on Thursday at Roanoke, 80/57 at Blacksburg). August’s average temperature to date is running about half a degree below normal at both sites now, as the last week’s relative coolness have nudged the numbers down. Temperatures the next week or so are expected to ride amazingly close to normal, with some scattered showers and storms on most days as daytime heating, moisture, terrain effects and upper-level disturbances bubble a few up. A cold front may add some influence to the weather mix by Tuesday … and what is now Tropical Storm Isaac may add its influence by late next week.
Forecast models have come into reasonable agreement over the past 24 hours that the center of Tropical Storm Isaac is likely to travel west of the Florida Peninsula (though it may yet scrape the Florida Keys, perhaps the southwest peninsula, and even Tampa Bay isn’t out of the woods yet when Republicans gather next week), through the central and/or eastern Gulf of Mexico. There, it will find a weakness in high pressure ridging to the north, and also some extremely warm sea surface temperatures, approaching 90 degrees in spots (the reddest areas are up to 31.4 degrees C, or 88.5 F). The high may provide enough upper-level influence to really cut off any winds aloft that could shear the storm, and that may allow a burst of intensification as it moves past Hispaniola and Cuba into the Gulf of Mexico. Isaac hasn’t shown much intensification so far — flights into Isaac have not found an organized inner circulation — but that is expected to change slowly over the next couple of days, especially when the storm is more over water than over the larger Caribbean islands. Most models now do not raise Isaac’s winds into major hurricane territory above 110 mph, but that could change if it spends a lot of time over those warm waters and has favorably calm upper-level winds aloft. Potential effects on Southwest Virginia — heavy rain, tornado threat, maybe even some fairly gusty remnant winds — would likely be maximized if it makes more of a northerly or at least north-northwesterly turn into the Florida Panhandle. The more northwest it tracks, the farther west of about Mobile, Ala., it makes landfall, the less chance we have of heavier rain. However, many models do sweep Isaac’s remnants back to the east with a cold front and/or low-pressure trough late next week. Many details are still in flux before landfall, let alone afterward.
August 23, 2012 - 11:41 PM
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Isaac has strengthened a little this morning, with 50 mph winds. The Euro model came back east with the 0Z run. The Mobile, Ala.-Pensacola, Fla. area seems to the bullseye on many models, but of course, there’s plenty of time for that to shift east or west quite a bit. If that holds, we probably see some rain out of Isaac Wed-Fri next week or so.
Something non-Isaac related to consider: This weekend, indication are that a small low-pressure system may move westward off the coast into interior Virginia. It’s likely to increase shower/storm chances Saturday over central and eastern Virginia, but may affect Southwest Virginia as well. Something to keep in mind.
Center of circulation overnight last night
was contrary to overall vector in the last day or 2..
Id guess new updates will show Isaac to be forecast
even further yet to the west as he moves eventually into Gulf.
By 20 degrees North he should have some more
significant steering winds.
…Meanwhile..Isaac (Hayes) anyone?
http://www.youtube.com/watch?v=PfK-UzQ48JE
Rained really hard in SC yesterday evening and light rain today Is this low that will back into eastern VA?
I was wondering what that little rotation was. Its raining in eastern Virginia now. Hope it can push a little toward Greene!
Just saw a meteorological term from AccuHenry that I didn’t know existed… gravity wave. KM, I’m assuming that gravity waves are the “streaky” clouds coming out of the outflow of the hurricane way up in the atmosphere? Supposed to be a sign of good venting and intensification? Wikipedia is a bit confusing on this term.
“Gravity wave” sounds like something right out of science fiction.
Matt..
Google gravity wave and hurricane..
there are several discussions in PDF format
there.
Kevin, to reinforce your 9:30 comment, “7″ just showed tomorrow and tomorrow afternoon getting very wet (using its “Forecast Model”) in many locations in Virginia, especially where I will be, in the Luray area. Big outdoor event could be a big WET outdoor event. As best I can remember, the model showed the main body of rainfall getting quite wet in central (but east of Lynchburg) and eastern VA, then migrating NW over the Piedmont north of C-ville and over the Skyline Drive into the central Shenandoah valley. Jared, if it “verifies,” I bet Stanardsville gets quite a bit tomorrow PM. It is already showering S and SE of Richmond now.
But the model showed possibility of rain in lots of other areas of the Old Dominion, too. Including most of SW Virginia.
Isaac continues to strengthen, up to 60 mph winds now.
I just looked up the Hourly Forecasts from The Weather Channel through tomorrow for both Luray and Stanardsville. I hope that TWC is correct about Luray (at max a 30% chance of rain), but I know a Greene Hills GC employee who hopes that it is wrong or underestimating the chances (also 30% max POP, but for more hours than Luray) for Stanardsville. Good luck to both of us, Jared.
I got soaked on my way into WVTF for the weekly Friday weather talk (4:30 p.m., FM-89.1).
I like where the CPC thinks the Isaac rain is going next week. Rah, rah.
http://www.cpc.ncep.noaa.gov/products/predictions/610day/610prcp.new.gif
I majored in science in college and those descriptions of gravity waves, fluid dynamics, and all those formulas are beyond me, so I’m assuming they are the pretty little wispy clouds fanning away from the outflow.
Joe: There is a photo floating around the Internet subsituting the face of Isaac from “Love Boat” on the National Hurricane Center tracking map.
Here’s your NOAA Glossary definition of “gravity wave:”
A wave created by the action of gravity on density variations in the stratified atmosphere. A generic classification for lee waves, mountains waves, and many other waves that form in the atmosphere.
I am not well-versed in how this relates to hurricanes. But in the animated image below from Isaac today, you can see what appear to be ripples in a pond near the center of the image. Those are “gravity waves” triggered by the overshooting tops of convection.
http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2012/08/800x900_GOES_B1_RSRSO_ISAAC_animated_2012236_111500_182_2012236_134100_182_X.gif
Hokieburg Mike, my apologies for previous hyping, if that’s what you were implying.
I did not intend to go “stretching out on a limb” & “Hype” but as Professor “Spock” Myatt has pointed out to this Star Fleet Cadet many times, models change therefore weather changes. If I had hyper-hyped & was totally acting like Kramer from Seinfeld in being “way out there”, “Spock” would have ended it right then & there. I per se, did not make a prediction as I am not a certified Met. I was just bringing to light what the Euro showed as IMHO, it is much better model beyond 5 days.
My reference to “HUGE” was that the Thursday 12Z Euro Op. run shifted way to the west & increased Issac’s strength/size as compared to previous runs. I also noted that Issac was somewhat similar to Ivan.
Here’s Wednesday’s 12Z Euro from the PSU E-Wall that I commented about:
http://www.meteo.psu.edu/~gadomski/ECMWF0.5_12z/tr24f144.php#picture
In fact, the 12Z Euro run on Wednesday showed a landfall at hour 198 between New Orleans & Gulfport with the pressure down to 960mb or 28.35”. That would have made Issac a weak to moderate Category 3 storm on the Saffir-Simpson Scale. Here’s reference to that scale from the Weather Channel:
http://www.weather.com/encyclopedia/charts/tropical/saffirscale.html
To compare the 3 hurricanes I was referencing, here’s an excellent link from the National Hurricane Center and subsequent illustrations:
http://www.nhc.noaa.gov/outreach/history/
Camille’s track
http://www.nhc.noaa.gov/outreach/history/camille_1969_map.gif
Katrina’s track
http://www.nhc.noaa.gov/outreach/history/katrina_2005_map.gif
Ivan’s track
http://www.nhc.noaa.gov/outreach/history/ivan_2004_map.gif
Professor Spock’s (KM) correct analysis comparing Issac to Georges as you will see below:
http://en.wikipedia.org/wiki/Hurricane_Georges
Enough about the past, can’t change it. Now let’s get to the present…Friday PM update…
Friday’s 12Z GFS Operational Loop:
http://www.meteo.psu.edu/~gadomski/MRF_12z/mrfloop2.html
12Z Euro Operational Loop
http://www.meteo.psu.edu/~gadomski/ECMWF0.5_12z/ecmwfloop.html
Here’s what they show.
Euro holds with landfall within 75 miles either side of Mobile Bay just barely Cat. 3 (966mb). Remnants go N to Memphis then rapidly NE to Nova Scotia.
GFS on the other hand goes east again with landfall #1 in the Keys (Marathon) then going due North over with #2 landfall at Naples/Ft. Myers & Tampa/St. Pete then a 3rd landfall in the Cape San Blas/Panama City area (all landfalls as Cat. 1) then curve towards the Mid-Atlantic.
Quagmire: Look again at the 850 mb winds map at hour 192 on the Euro model you posted. The core winds of the old Isaac are centered right over Va/WVa. The low in Nova Scotia is a different low than Isaac.
Yeah, its funny how weather channel has 30% of isolated storms and then on Facebook Dave Rookeries says 1-2 inches central Virginia with perhaps 3 inches doth of Richmond! Who is correct? Guess we will find out.
HPC is going toward the heavier amounts for eastern Virginia.
http://www.hpc.ncep.noaa.gov/qpf/fill_94qwbg.gif
One of our old friends reports:
The European model has remained very consistent– unlike all the other models –for the past four days. The model takes the system south of Haiti and Eastern Cuba and finally turns across Western Cuba into the Eastern Gulf of Mexico. From there the 0z Thursday AUG 23 run the European model shows a land fall either in the far western portions of the Florida panhandle or in Southern Alabama… as a category 3 hurricane.
NWS does not buy this yet.
Lexingtonian: Welcome and good comment. In addition to the NWS, the NHC (National Hurricane Center) wasn’t buying that European track either (although for the zippo cents that it is worth, I think the Euro track has a real chance of happening, and thus increasing the chances of Isaac becoming at least a Cat 2). As of a few hours ago, it shows Isaac going over the southern end of Haiti, most of Cuba, then into the eastern Gulf (bypassing most of the Gulf Coast of Florida) until it gets at least as far west as Panama City or Pensacola, where NHC predicts landfall as a Cat 1.
I am watching WDBJ7 right now …. I bet they show the latest thinking from NHC.
The latest NHC track is maybe 50 miles further east than what I saw at 12:15, but mostly the same. Isaac goes over the northern shore (inland just a few miles)of Cuba, then maybe hits Key West as either a trop storm or a “1,” then on up to Panama City. Cone includes as far west as New Orleans or as far east as Cedar Key, FL (100 miles NW of Tampa, SE of Tallahassee).
Schooled again by the master. my bad
Nice breeze out of the southeast; no rain here today.
None here either. Most pleasent day tho.
Lots of dry air in Isaac’s path.
http://forums.accuweather.com/index.php?act=attach&type=post&id=168462
That, and crossing Cuba, is probably a big part of the reason most models don’t get Isaac past Category 2, and many not even beyond Category 1.
Joyce has expired.
http://www.nhc.noaa.gov/gtwo/gtwo_atl_sub.shtml?area1#contents
But Kirk may be soon to form.
http://www.nhc.noaa.gov/gtwo/gtwo_atl_sub.shtml?area2#contents
If anyone who lives within 20 miles of Allstate (corner Electric Road and Keagy Road in SW ROA County), but at least 3 miles away from it, and wants a middle-of-the-day rainstorm on Wed. the 29th, then e-mail Kevin and ask him to forward it to me. I will come visit your neighborhood and it will pour while I am there. It happened Wed. at Promenade Park in SW Roanoke County, and it happened today big time between 2:10 and 2:35 PM on the NE end of Peters Creek Road (6800 block) fairly close to the intersection with Williamson. On the way home 45 minutes later, I could tell that it also rained within “my” postal delivery zip code of 24017, and about as far south as the RR tracks and the Roanoke River as I crossed over them on Peters Creek Road again. Zippo within 1.5 miles of my house.
I need another “toad-in-the-driveway” sighting …..
Of course by Wednesday we may all be getting the effects of Isaac Hayes anyway. I am going out-of-town tomorrow morning and won’t be back until Tuesday PM, so you all can rejoice in (probably) not having to worry about blog comments from me.
I used “Isaac Hayes” above because his name was the only “Isaac” that came to mind. Since we have been yakking about Kirk, Spock, Bones, Khan, etc from Star Trek, perhaps I should have called the Tropical Storm (or is he now a hurricane?) in the Caribbean “Isaac Asimov.”
Brandon, Comment 28.
A. Thanks very much for posting that. B. I wouldn’t think that all that dry air west of Jamaica should affect Asimov, unless it migrates further NE. And perhaps all that dry air west of Florida will move out within the next 3 days. Otherwise, I can now see why the “experts” think that Asimov won’t get stronger than a “1.”
Apologies if some of you don’t like me calling the big guy “Asimov.” Let your opinion be heard and I will drop it …. unless others check in and say that they like it.
Doug: Joe beat you to Isaac Hayes 29 comments earlier.
Isaac from the Old Testament, Isaac from “Love Boat”, Isaac Asimov are among other famous Isaacs.
With our little coastal low that could affect us tomorrow (and actually did some today), there is a tornado-warned supercell near Ocracoke Island, now.
Meteorologist Brad Panovich in Charlotte notes on Twitter that the circulation on the East Coast now is actually connected to what was once Tropical Storm Helene way down on the Mexican coast. Must confess I didn’t follow it in the interim.
Ricko already posted the precip outlook from today’s 6-10 day CPC issue. Everywhere east of the 3 West Coast states (in the lower 48, that is) has at least a 33% chance of being warmer than normal (including all of VA in that 33%) except for normal in all of Bama, most of Miss. and Tenn, SE Louisiana, and NW Georgia. Gee, you’d think that CPC is expecting a trop storm or hurricane to be having an effect there …..
On the 8-14 day, just as I predicted, the heat returns, with most of the eastern 2/3rds of the lower 48 expected to have at least a 40% chance (Virginia and WV and nearly all of NC are in that 40%) of being w-t-n. But at least we continue to have a 40% chance of being wetter than normal, too. As Garrett Morris’ character Chico Escuela might have said in the early days of SNL, “Early September (sometimes) been berra, berra good to me.”
Kevin …
Its too funny you mentioned
Isaac (Ted Lange) from Love Boat…
I didnt know how many people here remember who he was
but I guess no one is as old as me..
Funny thing was that after I went to work
and read your blog earlier in the day from home
..Ricardo..one of our analysts was making a Popeyes
chicken run. I went up to his desk to put in my order.
Just off to the right of the menu he had something on his
screen that caught my eye…it was 5 or 6 positions of
“Isaac” on its projected course with Isaac (Ted) and his afro in
full glory. I laughed out loud not having seen anything
but your description prior.
People gave me a little bit of a strange look.
…It’s very funny.
http://sphotos-b.xx.fbcdn.net/hphotos-ash4/208631_454488694572098_1438213422_n.jpg
Oh …and dont forget Sir Isaac Newton…
The man who discovered apples..
and was instrumental in developing Fig Newtons.