UPDATE 1 AM, 8/21: Tropics match tundra invasion; more showery, cooler than normal days will result
UPDATE 1 AM, 8/21: Carry this over another day, as Tuesday is likely to be similar to Monday — highs mid 70s to perhaps some low 80s after morning lows in the upper 50s and low 60s, scattered showers and storms. Sunday/Monday highs of 72 and 76 at Roanoke were the coolest back-to-back highs since 72 and 66 on May 13-14. Keep an eye on the tropics with 4 areas of interest -- one of which may be near Florida by early next week. I will try to get a larger update focusing on possible tropical troubles up sometime Tuesday. END UPDATE
I’ve often called fall in our region a battle between the tropics and the tundra. Though it’s too early to really call it “fall” yet — summer will almost certainly make another push or two our way — that battle has been fully joined. Through the past week, a mass of cooler air has been working south over the Canadian prairies, originiating from near the Arctic Circle. That air mass arrived Saturday behind a cold front — significantly warmed from its original chill, but still cooler and drier than typical August fare. Meanwhile, a surge of tropical moisture arrived early Sunday, pulled northward by a wave of low pressure that developed on that cold front. The result was widespread rainfall in Southwest Virginia — the first date since May 14 when both Roanoke and Blacksburg topped an inch of rain — and atypically cool temperatures, shaded by rain and clouds, with a high of 69 at Blacksburg (13 degrees below normal) and 72 at Roanoke (14 degrees below normal). Without the cooler, drier air mass from the tundra that condensed the moisture, it would have been a sticky, partly cloudy day with highs in the 80s and scattered afternoon storms. Without the tropical surge, it would have been a relatively mild, dry sunny day with highs in the 70s to low 80s and lows in the 50s. The two air masses intersecting is what caused Sunday to turn out like it did. Though we’re going to miss out on what could have been some unusually early crisp morning lows that would have occurred if the tropics didn’t join this battle, what occurred Sunday is indicative of what often happens in autumn, especially early in the season. So in a way, the rainy, cool Sunday was a taste of fall.
The tropics-tundra battle will continue this week. As is typical in late summer, the tropics will ultimately win this battle, likely leading to a return of warm to hot, sticky weather, possibly as early as the coming weekend. The result in the short term, however, will be rather stable temperatures, mostly mid 70s to low 80s for highs and upper 50s to mid 60s for lows — highs a little below normal, lows near normal — through at least midweek, perhaps slowly warming by Friday. There will be intermittent chances of showers and storms, especially today (Monday) and Tuesday as some daytime heating, weak disturbances and perhaps another wave along the front to our south squeeze out some of the moisture. It’s not likely we’ll see a repeat of Sunday morning’s widespread downpours — projected amounts through the next 5 days total no more than half an inch across our region. But some showers moving up the Blue Ridge from North Carolina early this Monday morning might top that projection in a few spots even before the sun rises. (Latest radar linked here)
Long term, we need to be watching the tropical Atlantic, especially the two disturbances west of Africa that may have some chance of affecting the U.S. by next week. It’s a long way out and a lot can happen, but it is the season for the tropics to have a big upper hand it will be sure to lose to the surging tundra by October and November.
August 20, 2012 - 12:43 AM
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Reposting this from Joe, our native SW Virginian dispatching flights from Dallas-Fort Worth International Airport, after he posted on the last thread. It’s about the heavy rain and storms in the DFW Metroplex on Saturday. Particularly note the quote from the guy hit by lightning.
http://www.star-telegram.com/2012/08/18/4190589/some-forth-worth-streets-flooded.html
It won’t be a full repeat of Sunday morning, but watching the radar before I sign off just before 1 a.m., I’m wondering how far north up the Blue Ridge the showers near Mount Airy will get tonight. Certainly looks like Grayson/Carroll/Floyd/Patrick counties will get some rain. Would not be surprised if even the Roanoke Valley got some showers out of it later.
@ Newt, I figured out who you were after my first cup of coffee. Small world.
Speaking of cup of coffee, it was nice to drink coffee on the back deck while walking the dogs without starting to sweat. It’s amazing how the summers just race by.
Days like yesterday really sap decimals off average temperatures. Roanoke’s August average temperature at Roanoke is down to 76.1, essentially a normal month — and the summer average lost two-tenths, down to 76.5, which would tie it for 10th hottest if it ended today. But it doesn’t end today, and is likely going to keep losing decimals much of this week.
Cloudy and cool today finished up with one and three quarter inches of rain from yesterday’s event very little runoff. Grass looks better but pond still suffering . Some of the maples and poplar trees are starting to show reds and yellows in there leaves. Seems a little early and if it stays dry into fall the colors of the leaves will not last as long I think
Randy, the dry weather certainly affects trees as well as leaves. And you probably will see leaves[poplar, maple, sumac, sassafras] start turning/dropping earlier than normal. The tree basically shuts down leaf development and uses the ground moisture for the trunk and limbs during dry times. Not too late to have a good color this year but it needs to start now. I think you’re right tho, without a good shot of rain it won’t be an eye opener.
Downpour in south Roanoke County now.
Not even a sprinkle on da Knob.
Has the front moved a little east since today’s storms really started taking shape east of 81?
Wow, another nice rain moving through Greene now! Dont think its going to last long, but its rain none the less! I will be glad when we get those canadien cold fronts that knock this humidity out of here. This front doesnt seemed to have budged the humidity at all! Guess I still have another month to wait before that happens.
We measured a relatively puny 0.42″ from the system at my house. While just a few miles away, easily 3-4 times that fell. And it poured and poured at our campsite, I’m just glad the tent canopy and our gazebo canopy blocked 99% of it, and the sun yesterday afternoon gave me a window to dry everything out before I re-packed everything for storage.
I see the heat comes back in next week. Ok, I don’t think it will top 104, I don’t even think we break 95, but I guess we can’t call the Summer Temperature Contest just yet.
http://www.cpc.ncep.noaa.gov/products/predictions/610day/610temp.new.gif
I was out on a mountainside between Clearbrook and Boones Mill during that downpour. It was a cold, miserable 40 minutes.
Rick: That’s probably more of a tropical warmth than a heat wave. Look at the precipitation map:
http://www.cpc.ncep.noaa.gov/products/predictions/814day/814prcp.new.gif
Models want to bring some of these tropical systems flirting with the East Coast.
It could well be that the above-normal is more about humid tropical lows than really hot highs. And, of course, what is “normal” is slowly slipping downward. (And it is lower already in the Northeast where the core of that above-normal is painted)
For the contest — it has to get to 104 at Roanoke for there to be any effect on the contest. Very, very doubtful. Sticky heat won’t get us there … only compressing hot, dry winds over the mountains like June 29 will.
Looks like I got about 0.4 inch in that early afternoon downpour.
Matt: on the current surface map, you can barely make out a beige dotted line over western Virginia, a weak low pressure trough. That was a big part of triggering mechanism for today’s showers/storms.
http://www.hpc.ncep.noaa.gov/sfc/90fwbg.gif
The front has settled well south now into South Carolina and central Georgia.
One of those unusual days when Blacksburg had a warmer high than Roanoke (77/76), probably owing to the mid-day shower in much of the Roanoke Valley (airport got .59 inch of rain today). Roanoke temperatures have averaged 6 degrees below normal last 2 days, with highs averaging 12 degrees below normal. Blacksburg’s low of 59 was right smack on normal for Aug. 20, but high of 77 was 5 degrees below normal. Trend of near-normal lows, below-normal highs probably has another 2-3 days in it before highs start nosing upward to near norms (low 80s Blacksburg, mid 80s Roanoke).
A nice cloud tutorial from Accu.
http://www.accuweather.com/en/features/summer-road-trips/road-trip-survival-recognizing/66609
Kevin…
Are the tomato plants still alive there?
Have the apples suffered from the relative
lack of rain?
Our late-planted, potted tomato plants are doing pretty good despite some hail damage last month. Don’t have a feel for more long-term, garden tomatoes. Bet some folks on here can give some insight.
Apple trees I see don’t look too bad. I’ve heard the crop is peaking unusually early because of early spring warmth. I know the apples in the Great Lakes region are at near-record low yields because the trees greened up and bloomed early in the warm March and then froze in April. We didn’t get the same level of cold in April/May so the apple crop in Virginia wasn’t heavily damaged like it was in 2007.
Yes Kevin..
that trend seems to hold most places I know of.
Here in Texas everything came in early for the same
reasons. We had not much of a winter and almost
no hard freezes.
Because of that some surmise that our problems
with West Nile Virus are quite exagerrated this summer.
Spraying was scheduled in widespread areas this year,
though temporarily postponed due to the rain a couple of nights ago.
http://www.the33tv.com/news/kdaf-aerial-spraying-for-west-nile-virus-resumes-in-dallas-county-20120819,0,4798558.story
Funny you should ask,Joe,I was just commenting to my wife tonight how my ‘maters have stopped their ripening …had a great year,one of my best years ever,but usually after the middle of August that is it. Of course,mine have been in the ground since mid April and survived a couple of close calls with frost then too!! Dreading the ole store bought Roma’s in a few months…
A bag of about a dozen small Gala apples was 4.97 at Walmart! That’s really high so maybe they come from the Great Lakes area. We have a VT alum apple grower in the Southside VA. He grows Fujis mostly, saying that while they don’t look as pretty as some of the other varieties, they test the best and I have to agree. He usually brings us a box come football season which is coming up. I’ve heard that dry weather at the end of summer makes the apples (and grapes) sweeter.
Kevin, I am not sure about all of Washington Co but the late freeze we had wiped out our fruit crop here in Rich Valley. No apples, pears or peaches. I have one crep mrytle I have nursed along and they do not usually do well here. I had put out in the spring and all the tender leaves froze off. It put out again and is just now blooming. Our deep valley location hurts us so often on those cold night.
Tomatoes in Floyd County at least are suffering from “late blight”- an airborn virus that comes in from humid, warm air from the Gulf. The outbreak hasn’t been as devastating as the 2009 east coast tomatoe failure, but it’s bad enough that a lot of growers up here have already lost their crops.
I am sure there are pockets of bad apple crop in Virginia but it doesn’t appear to be the widespread decimation like 2007 in Virginia or this year in Michigan.
The jury is still out on our 3 ‘mater plants, but so far, so good.
I had planned to do a full update of the blog tonight, but I am wiped out. Perhaps I will get to it Tuesday, looking ahead to possible tropical troubles. Tuesday will be similar to Monday in SW Virginia.
48 this morning up here on the ridge.
Yep, I see Blacksburg’s airport is down to 54. NWS office official temp might be a little cooler. My 49 guess for Blacksburg 8 days ago doesn’t look too bad now. Just think how cool it could have gotten with clear skies and without all this moisture.
Burr, and my 50 was beat with a 46.5 at the nearby Kings Weather Station.
54 this morning, felt really nice. Watching TD 9, upper level steering currents will make this one that bears watching. The tropical wave right behind it could ride TD 9 / Isaac’s coattails too. We’ll see, but it looks like for the interests along the US coastline, the Atlantic hurricane season is about to get really active, really quick…even though it’s already been a fairly active season, not much has been of significant concern to the US.
My tomatoes are still ok, no blight that I can tell. My peppers have now decided it is time to bloom and produce like crazy, not sure how this weather may affect them.
My parched yard is definitely enjoying the rain. My front yard is brown and crunchy in several large spots and the crab grass that grows in the back yard is looking miserable too. We could have a steady rain for a week and I’m not sure it would get much better.
Quag’s Tuesday morning update for August 21:
Maters down this way are past peak ripe, red and yummy. AM temps down this way in Eastern Goochland have been in the mid 60’s the past couple of mornings with some rain, thanks to the front stalling practically right over us. Afternoon temps have not gone above 81 since Sunday. I love the cooler weather, even if I’m a little closer to the coast. Football season is just around the corner!
Say Hello to Issac!
http://www.nhc.noaa.gov/
What is it with these “I” Storms and Virginia? Kevin talked about this earlier and had a great article. Issac does bear watching but as of right now, he is not expected to affect Virginia
In a significant way. But remember, this is still a week out.
Dave Tolleris at wxrisk.com has a great write-up from Monday night on his website and
Does his usual outstanding job in explaining what Issac is expected to do.
http://www.wxrisk.com/
Here’s the latest ENSO Report posted on Monday August20:
Powerpoint version
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.ppt
PDF version
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
International Research Institute for Climate and Society:
http://iri.columbia.edu/climate/ENSO/currentinfo/figure1.html
Consensus is still predicting for El-Nino conditions to develop any minute now and continue thru next year.
Another interesting report out is the CPC seasonal outlook for the months ahead, especially for the Winter of 2012-2013.
http://www.cpc.ncep.noaa.gov/products/predictions//multi_season/13_seasonal_outlooks/color/churchill.php
just thought I would share. I’ll update on Issac later.
Quags, thanks very much for posting all that stuff. I would love it if the CPC 3-month maps “verify” for this winter, but I don’t believe them for a second. I have seen them predict a warm month, and it turned out very cold, not only here but on a widespread basis, and vice-versa. I don’t know if I would call them as “untrustworthy” (imho) as an Accuweather winter outlook, but I’ll believe a local guy with a beard here in Roanoke who runs the Weather Blog. And he is smart enough to wait until late October or November before sharing his thoughts.
I too looked at the weekly ENSO report. The latest weekly temp in the 3.4 measurement area decreased a bit from the previous week, from +0.8 to +0.6. I bet it goes up slightly again next week.
And the CPC multi-day maps continue to show wet and warm for our region, although the 6-10 day has us just barely in the white, with the tans (warm) to our west.
My back yard still looks lousy, but not nearly as horrid, putrid (fill in your own Leonard Pinthe Garnell adjective) as Saturday. Front actually looks half-decent for color.
As of 5 PM Sunday afternoon, Charlottesville had a high on that day of 70. I see that Blacksburg was even cooler, high of only 69. Any other sub-70 highs around the region? Rick? clarkdoc? Zach?
Michael Hoback, your 10:26 comment last night. Were you talking about a “late freeze” in the spring? How late was it?