A swirl of clouds from the ocean may bring us some rain Saturday … but it’s not Isaac (yet, at least)
The swirl of moisture shown earlier this evening on the satellite photo at right may bring a rather rainy day to parts of central and eastern Virginia on Saturday. And it may spin enough moisture even into western Virginia for enhanced showers, or at least, more clouds and cooler high temperatures — not that highs have been hot at all lately, but they may remain in the 70s on Saturday with clouds and showers. This swirl of clouds is a low-pressure system that may drift inland a bit this weekend. At least one meteorologist has noted it’s associated with the mid-level circulation of the barely-known Tropical Storm Helene that came inland in Mexico several days ago. The atmospheric spin it contains was significant enough for a supercell thunderstorm to develop tight enough rotation that a tornado warning was issued for Ocracoke Island in the Outer Banks on this Friday night. We experienced some effects of it Friday, as its rotation spun showers to the southwest, including one that gave a quick downpour to parts of Roanoke between 2 and 3 p.m. While this system is not a wholly tropical entity, its possible origin and the fact that it is moving westward indicates we have moved into a tropically influenced weather pattern.
Tropical Storm Isaac is nearing hurricane strength just south of Haiti late on this Friday evening. It is crossing a thin peninsula of southwestern Hispaniola, not the densely mountainous middle, that probably won’t sap its strength much, but then it is projected to move diagonally 
northwestward across Cuba. It may have a hard time getting anything stronger than minimal hurricane strength until, possibly, it blows into the very warm, open waters of the Gulf of Mexico late Sunday. Most forecast guidance is pointing to a Florida Panhandle/south Alabama landfall by Tuesday or so. Just as there remains some uncertainty about its track over the Gulf, its path and effects once it moves inland are a little fuzzy … but this Climate Prediction Center 6-to-10-day precipitation map certainly shows a potential wet bullseye over the southern Appalachians and Mid-Atlantic regions. Some forecast guidance turns it sharply northeastward once inland, keeping most of the rain south and east of our part of Virginia, while some of it carries it farther inland to the northwest, and brings Isaac’s remnant low toward us a couple of days later. There are a few more days to sort that out. Southwest Virginia usually — though not always — gets a pretty good soaking when a tropical system comes into the Florida Panhandle.
August 24, 2012 - 11:21 PM
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One possible great effect from Isaac Asimov is that he may put a huge dent in the Exceptional Drought conditions in part of Georgia.
And please notice where the bullseye is for the heaviest rainfall amounts in Virginia are? Right over Michael Hoback’s house. clarkdocvet and Rick and Zach get in on that action, too, and possibly Johnny of Hillsville. The area of Virginia that has been getting the most rain this summer (it seems) might get the most from Isaac.
One positive note for me …. Draper just aerated their greens on Monday and Tuesday. Those greens will heal in a hurry if that heavy rain comes their way.
Just took Blondie-boy out, and saw another toad!! That’s the good news. The notso good news is that tonight’s toad was tiny … the one I saw last Saturday night was a Queen Latifah. Does this mean only light showers for me, not more than 1/3rd inch?
In recent years we have watched model paths of hurricaines fluctuate widely, with a few skewing far to the right or left of the NHC’s suggested course. With this storm, they are all tightly packed, with a width of no more than a couple of hundred miles.
There are, however, two big disagreements this morning. The GFS and the European model present significant alternative forecasts. The GFS saps Isaac’s strength over southern Florida while the European increases its energy over the gulf.
One commenter explains it this way: “The GFS model is merging or phasing Isaac on theFL panhandle with a trough or cold front that moves through the great lakes and the northeast early next week. The model does not seem to understand that these are two separate systems and this over phasing tendency is very common with the GFS.”
Does this mean we should pay more attention to the European model in our forecasting? I think I’ll stick with the middle of the road idea being rendered by our NHC.
The HPC has Isaac putting on the brakes at the North Carolina boarder and then going hard right out to sea. I want a couple inches from this………..not the 8″ Charlotte might get.
http://www.hpc.ncep.noaa.gov/qpf/p120i12.gif
Rick: While there is some model support for the storm possibly swinging south and east of us … I don’t think that is what the HPC rain map is showing. Based on HPC weather maps, it doesn’t show Isaac’s remnant low positioned far enough north to bring us much rain until late Thursday/early Friday. The rain map you posted ends Thursday morning. It just isn’t close enough by then to bring the heavy rain, but it’s on its way.
Thursday morning map has the low still in central Alabama and a warm front well south of us.
http://www.hpc.ncep.noaa.gov/medr/nav_conus_pmsl.php?fday=6&fcolor=wbg
Friday morning map has the low near Nashville and the warm front north of us.
http://www.hpc.ncep.noaa.gov/medr/nav_conus_pmsl.php?fday=7&fcolor=wbg
Thank you Mr. Postman, Blondie & the Frogs too!
That is if you drove the car down Goochland way.
Nice rains in Central VA this morning. As of 08:00 AM,
the guage is at .62″ with more to come.
Here’s a video for Blondie and our favorite postman
http://www.youtube.com/watch?v=oMd9LydS8E4&feature=related
Lexingtonian: The Euro model seems to generally do better 3 days plus out. It’s not as perfect as some of its biggest fans claim (showed repeated big snowstorms for us in 2010-11 winter that ended up being crushed by Arctic high pressure to the north). It has bounced back and forth a little too much between a far west path almost to Texas and a more easterly path toward Pensacola, Fla. I would agree with the commentator that the GFS model doesn’t seem to be depicting typical tropical system reality, at least in late August, with its phasing Isaac into a trough so quickly and easily.
My lean since the start with Isaac has been the Florida Panhandle — Appalachicola was my original guess, though it may end up being west of there. I’m sticking with that.
Lexingtonian…
To answer your question about paying more attention to the Euro…Yes and no.
The Euro is just one of many models that is a great tool for weather forecasting. While it is an excellent model, especially beyond 4 days, it too is not perfect and is not always correct in its solution. Taking the safe route in using all available data is always a sure bet like what NOAA does. Something I need to work on as I am not disciplined in this practice as others are.
Looks like some good rain heading our way in Greene if the current mass of rain holds it course! This will probably be our only chance for rain until the remnants of Issac come this way, if that even happens. So it will probably be friday/saturday event for us up here in north central Virginia. Am I correct on this Kevin?
If Isaac’s moisture comes our way, it will probably be in the Thursday-Saturday period for most of Virginia. Timing is still uncertain, as is track, of course. And you will probably get some of today’s rain, because the low is moving more north than west, up the coast.
Mmmmm….looks like the Hokies vs. Georgia Tech might be one of those ‘hurricane’ games…
…even if the weather is crazy, Lane Stadium will still be like this on Labor Day: https://www.youtube.com/watch?v=SrTmaypDWFI
Looks like Isaac may just come on to our family reunion next weekend after all. Well I sleep in my house and the out-of-towners camp in the field across the road. Guess who will be dry?
No..no..no! Please – no rain next Friday and Saturday. I’m having a yard sale in Salem!
11:00 AM rain update in Central VA…Good News for this part of th state that needs the rain badly as some localities in Central VA are on H2O restrictions.
Now up to 1.36″ in Goochland Co. since 2:00 AM with moderate to heavy rain & thunder. South & East of Richmond getting hammered with flood warnings coming up in some areas. Over 4″ now reported at Newport News since it started.
Tropical update from NHC at 11:00 EDT
http://www.nhc.noaa.gov/
http://www.nhc.noaa.gov/text/refresh/MIATCPAT4+shtml/251458.shtml
12Z GFS now a little more west keeping Issac off the coast as it goes by Naples/Ft. Myers/Tampa with landfall still on track for Panhandle area then coming up the Appys for significant rains for the south and parts of the Mid-Atlantic.
will post 12Z GFS op runs shortly…pouring down now hard just had wind gust 33mph
Latest map from NHC at 11:00 AM
http://www.nhc.noaa.gov/graphics_at4.shtml?5-daynl?large#contents
Southeastern VA & Chesapeake Bay under the gun…New Meso Discussion
http://www.spc.noaa.gov/products/md/md1810.html
Saturday 12Z GFS Op run.
http://www.meteo.psu.edu/~gadomski/AVN_12z/avnloopnew.html
I mentioned previous about this run that it showed landfall in the FL Panhandle. To correct myself, 12Z GFS shows landfall AL/MS coast with Mobile Bay as focal point +/- 50 or so miles.
Jared – looks like you are getting some much needed moisture up your way. East coast of VA looking like you are getting deluged. We have had only a couple brief showers up here on the ridge this morning.
Correction #2, 12Z GFS has Issac’s remnants staying west of the Mid-Atlantic/west of the Appalachians to the TN/OH Valley but no significant rains for the Mid-Atlantic, my bad #88954
Kevin, wouldn’t the trough coming across the plains push Issac our way? Quags says the GFS has Issac going up into the Ohio valley! Would be terrible to miss out on that rain, but I guess they need it worse out that way.
Wow…that GFS is a far cry from the one they put out last night, which had Isaac making basically 3 landings–Key West, near Tampa, and on the Panhandle. It surprised me to see it go so far west after the last few runs for virtually all models kept moving east. That is starting to put NO in play, and is also allowing for the possibility for a much more powerful hurricane than what there was before.
Oh well, the rain on radar has fallen apart! Reports of decent rain from Charlottesville south and east, but guess what! The ground is dry in Greene county, at least in the western section it is. Its simply amazing how the Greene county forcefield struck down this rain, it looked ominous this morning and heading in our direction. Sigh, what gives?
I have already lamented about Isaac coming to our family reunion but we do need the moisture. Had .10 last night in some scattered storms but grass is showing stress here in Washington Co now. Maybe we will be close enough to the western edge of the system to give us a rain. This time of year, you take what you can get. Enjoying a bright sunshine today with temps in the low 80′s. We are way too west of that Richmond system for clouds and rain today.
The speed and strength of the trough in the central U.S. is going to be a key in how much effect we get from Isaac. But if it heads NW toward MS/LA area, it’s going to have a lot of momentum NW before it can get turned back around, and might curve north of us.
12Z European model track on Isaac inland would be a major soaker for SW Virginia. This is for next Friday morning.
http://blogs.roanoke.com/weatherjournal/files/2012/08/Euro144hour0825.gif
If this were to verify, it could be incredibly bad for Roanoke and area up and down the Appalachians.
NCEP HWRF total precip:
http://www.weatherbellmodels.com/weather/hwrf/hwrf.2012082512/isaac09l/total_precip_p_43.png
Very similar track to what the 12z Euro is showing. See Kevin’s comment #26.
http://www.weatherbellmodels.com/weather/hwrf/hwrf.2012082512/isaac09l/pwat_mslp_p_41.png
Let’s hope that Issac goes where he is needed – the midwest could use some rain as well as Georgia. Meanwhile, what is with the rain today up in Central VA? Watching radar and wondering where the blob of rain is going.
Jared, how is it looking up your way? Any rain?
Always a problem with tropical systems — even drought areas don’t need 8+ inches all at once. Hopefully Isaac can maintain some decent speed inland, and not meander, so that the amounts are more 3-5 inches rather than 8-12 inches, or more.
If the models Ben posts verify — it would be a flooding disaster for our region, no matter how dry we go into it. The chances of that exact track occurring 6 days out are pretty slim — but in the ballpark of the possible.
I would say our chances of getting some rain linked to Isaac are high, maybe even 70 percent. Even if the storm chugs more to the west inland, some of the remnants may bend back our way with the trough, or it may influence southeast upslope winds that create some showers. Our chances of getting a widespread flooding problem — say 3+ inches areawide — are still down around 20-30 percent or less. Just too many scenarios that can transpire. But the Appalachicola-Mobile zone for landfall usually translates into soaking rains for us.
Didn’t take that batch moving in from the west long to dry up.
Today’s system was handled pretty well by the models. It wasn’t projected to do more than weak showers west of Lynchburg — actually seems to have gotten a little farther west of that up toward Lexington.
Re: Quagmire’s 11:18 a.m. comment.
Tornado reported on Virginia’s Eastern Shore, with a trailer damaged and 1 injury, right where the SPC was noting the severe risk.
http://www.spc.noaa.gov/climo/reports/today.html
Even though this has been discussed already, here’s the Sat. 12Z Euro Op Loop from PSU:
http://www.meteo.psu.edu/~gadomski/ECMWF0.5_12z/ecmwfloop.html
Ditto to what Kevin said.
In the last hour or so, thunderstorms have re-developed in SE VA & are moving
NNW towards the Richmond area. This area may pivot around the Low bringing more rain to not just the Richmond area but back west along the US-15 corridor. Some areas in the Wakefield WSO area had over 5+” rain today. 1.88” here.
Jared French & the C’vile area may get more rain out of this.
Here’s what they have so far at the Wakefield Office:
000
NWUS51 KAKQ 252103
LSRAKQ
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE WAKEFIELD VA
503 PM EDT SAT AUG 25 2012
..TIME… …EVENT… …CITY LOCATION… …LAT.LON…
..DATE… ….MAG…. ..COUNTY LOCATION..ST.. …SOURCE….
..REMARKS..
0315 PM HEAVY RAIN WAKEFIELD 36.97N 76.99W
08/25/2012 M6.37 INCH SUSSEX VA NWS OFFICE
SINCE 1 AM EDT
http://radar.weather.gov/radar.php?rid=AKQ&product=NCR&overlay=11101111&loop=yes
Was surprised to see it moving as close as it did. Forecast sure didn’t mention it getting to the Rke. area in anything but pop up stuff. They were dead on the button.
Kevin, HPC has a lot of the southeast getting nearly 12″ of rain on days 4-5 map here. Is that really possible?
Always possible with a tropical system. Keep in mind Camille in 1969 dumped up to 27 inches on Nelson County, Virginia (with unconfirmed reports up to 36 inches).
Just my gut, but I’m thinking Issac will be an event for us rain wise.
One of the more extreme scenarios right now:
http://i48.tinypic.com/j5jc6p.png
Just putting this here to show the wide range of possibilities that could occur, but no guarantee. I’d say anyone from the FL panhandle to western Louisiana should be preparing for the worst.
Ben…
Will agree that everybody along the Gulf Coast from LA to FL better be getting their act together now, especially the Gulfport/Mobile/Pensacola/Ft. Walton Beach area.
The HWRF IMHO may be a little over done on that scenario but anything can and still may happen.
We are about to get pounded again with another line of storms coming thru Central VA. Can hear the thunder now about 15 miles away.
Newest track cluster on hurricane models: New Orleans getting nervous.
http://raleighwx.americanwx.com/models/atcf/00zatcfearlyinvest1best.gif
I am becoming increasingly worried about New Orleans. 00z model agreement is really tight together.
http://i49.tinypic.com/2qmhs8x.png
It’s important to note that the longer Isaac stays out over the Gulf, the stronger he’s going to be. Conditions are ripe for rapid intensification.
I don’t like what I see right now.
Another thing that worries me is that Isaac couldn’t have steered a better path between Hispaniola and Cuba if “he” had tried. It seems like everyone was counting on him either hitting the “hurricane killer” mountains of Haiti and the DR, or at least weakening a lot on the smaller mountains of Cuba, but with the exception of hitting a small part of the flatter land around Port-Au-Prince, the center of circulation has managed to stay in water almost the entire time. The only thing now lying between Isaac and the gulf coast is a slight brush with the Keys, and a lot of very warm water.
Tonight’s Rockbridge forecast says: “A slight chance of showers. Partly sunny, with a high near 84.”
This certainly does not agree with the graphics posted above.
Agreed, Ryan. I was going to post a similar comment — though, actually, not as eloquently as you put it.
Kevin, you thinking about changing your landfall prediction yet?
Flutie: Yeah, it’s going to be west of my Apalachicola guess — which I would call only a guess, as I made it 3 days ago. I’m thinking Gulfport, Miss., to Mobile, Ala., at this point. Maybe Lake Pontchatrain, La.
Lexingtonian: Which graphics do you refer to?
Had a couple of different showers today but overall not a lot of rain.Went down to Manassas to visit my parents and they had a nice shower around 4:00.Just has a little rain in the past hour,temp down to 66.Temps stayed in the 70′s all day but the humidity was higher today!Hope everyone has a great weekend!
Impacts in Roanoke already? I have a co-worker stuck in south florida with flights out already being cancelled, so he will not be back tomorrow as planned.
I have a silly question; I just checked the 11pm NHC projected path and see it’s still solidly in the panhandle of FL. OK. But the model paths a la Wunderground’s 11pm update show it clearly west of this…what gives? Is this just one of those situations where the models and NHC aren’t in agreement?
This is the first yr I’ve watched the models runs myself, so…yeah.
The new NHC map is actually a little farther west than earlier today. The cone no longer even scrapes Tampa, Fla., for instance, and the western side almost gets to New Orleans. The center point has shifted a bit farther west down the Panhandle, too.
http://www.nhc.noaa.gov/graphics_at4.shtml?5-daynl?large#contents
Like most federal forecast entities, the NHC is loathe to make any huge jumps from one time to the next, preferring to nudge things a little at a time. Also, the Euro came back to the east some today. If the model trends continue over the next 24 hours, I’m sure you’ll see this track nudge even farther west.
Latest GFS run has a New Orleans landfall.
http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gfs/20120826/00/gfs_atlantic_072_850_temp_mslp_precip.gif