Tropics are rocking; summer makes a brief return to SW Virginia, before a taste of fall next week
The National Weather Service at Blacksburg has not reset its storm total radar composite (linked here) since Saturday, so it gives a good picture of the spotty nature of rains we have experienced with the remnants of Hurricane Isaac. My house is in one of the light blue areas under 0.30 inch. This picture has changed some even Wednesday — most of the green 1-2-inch area just north of Roanoke was colored in Wednesday evening in a stalled squall that led to a flash flood warning for southwest Botetourt and northeast Roanoke counties for a while. Overnight, 
the color scheme may change a little bit, as a disturbance works in from the west with scattered showers and maybe a few storms, slowly diminishing remnants of what was once a fairly stout squall line in the Ohio Valley earlier today.
We can finally stop talking about former Hurricane Isaac — and start talking about possible tropical storm Nadine. The chip off the old block is (as of late Wednesday evening) given a 50 percent chance of becoming a tropical cyclone in the Gulf of Mexico. Being a tropical cyclone doesn’t necessarily mean it will be named — it may only become a depression — but the National Hurricane Center on its Facebook page already has a rather lengthy explanation of why it would be given the name Nadine and not regain the name of the former hurricane from which it sprang. The hurricane center is expected to send some surveillance flights into the storm on Thursday afternoon to ascertain its organization and strength. Its likely the system will be shunted eastward toward the Florida peninsula as new cold fronts and a southerly dip in the jet stream by the weekend nudge it along. Out farther in the Atlantic are hurricanes Leslie and Michael. Leslie, now poking along, will sweep near or over Bermuda and then speed rapidly in the general direction of Newfoundland. Michael will stay with the fishes in the open Atlantic.
That dipping jet stream and Leslie’s circulation are going to team up to pull down some significantly cooler, drier air from Canada early next week. This temperature anomaly map from the 12Z run of the European model shows blue over much of the East, indicating cooler than normal temperatures by Tuesday morning. Lows in the 50s and highs in the 70s will be widespread, and it may go a little cooler than that in some of the normally cooler spots around, especially if we can get a clear night with calm winds next week. The normal high has dipped below 80 at Blacksburg, with normal lows dropping into the low 50s by next week, and Roanoke’s norms are around 80/60 the next several days, so this is not great chill we’re talking about, just a little taste of fall. When the cold front starts cutting into this leftover tropical moisture, thunderstorms will likely develop, and some of them could be strong to severe. After whatever showers and storms we get overnight, we may get a break in the daily rounds of showers for a couple of days — they will probably be fewer in number over Southwest Virginia on Thursday afternoon, and maybe very isolated or non-existent by Friday afternoon, as high pressure builds in with warmer and somewhat drier air. That high will lead to summerlike temperatures, possibly reaching or exceeding 90 in Roanoke and points south and east one or both of the next 2 days, especially Friday. I’m not about to call this summer’s last stand, but it will be a brief encore performance.
September 6, 2012 - 12:13 AM
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Cooler, drier air will certainly be a welcome relief. Kevin, you are averaging over 50 comments per post now. What is it going to be like once you start mentioning snow?
If it develops to a named status, why not call it “Isaac, Jr.?”
Getting bombarded with heavy rains up here in Greene county this morning! This will be perfect after that cool dry air gets here in the next few days. Kevin, do you think this will be the end of the humidity or will it make a comeback later in the month? By this I mean the extreme humidity weve had this week.
Ended up with “0.06″ inch of rain yesterday. Every little bit helps.
Ended up with .30″ overnight in storms that rolled through between midnight and 1 am. This gives us a grand total of 3.10″ since last Saturday. Could top 4″ in a week depending on what those storms do Saturday.
Kevin,
I was watching various satellite and radar images of Isaac Jr yesterday and last night and the rotation seemed to be clockwise. Now it appears to have no rotation. I would guess that it will evolve to the usual counterclockwise as the day progresses.
Were there any dynamics that would have caused the clockwise rotation of a low that was straddling the coast? Would half / half sea have had any influence? Is this unusual or did I just notice something that is not uncommon?
I was the proud recipient of some rain yesterday! I woke up this morning and my deck and driveway were still wet, so I hope that means we received some significant rain last night. I’m going to have to invest in a rain gauge soon!
I’m looking forward to the cooler weather next week! Bring on fall….and then WINTER LOl
Mike: Would the clockwise spin you noted have been the evacuation of clouds at high altitudes by high pressure? It’s typical for tropical systems to park under high pressure aloft.
It doesn’t have a very organized internal surface circulation. The National Hurricane Center has trimmed the chance of development back to 40 percent his morning. We may never see the daughter of Isaac come of age.
Kevin,
It may have been as you described. What I observed was from satellite views. It actually occurred over a couple of days, I think. I was looking for an animated archive and this link covers just barely enough to show what I’m talking about. An earlier 48 hours or so would be better. http://www.orbit.nesdis.noaa.gov/smcd/opdb/aviation/loops/realtime/atlwv_loope.html
Kevin,
One more chart that would seem to support the clockwise flow on Isaac Jr. I hope you can see it before it updates. I think this wind chart is surface winds, but I’m not sure. Interesting anyway. Interesting flow pattern in the Dakotas(?) region. If there is a low there would that confirm that wind map is surface data? I would appreciate that confirmation as to help me interpret this bit of my personal need to know!
Sorry, the wind map: http://hint.fm/wind/
“Nadine”
Likely kept us from getting rain last evening here in North Texas.
Her circulation kept a cluster of thunderstorms at
bay up along the Red River.
We have had 32 days of 100f plus here this year..
but cool air is on the way maybe upper 80s by this weekend.
Tomorrow could set another record though..
as of now the forecast is to possibly reach 102f..
and our oh so witty writer for the Star-Telegram tells us not to
get out our coats and jackets just yet.
The latest triple digit temperature here in the calendar year is Oct..
Oct 3, 1951..it was 106f.
Precooked pumpkin pies?
Don’t think that 0.07″ we had around 2 PM qualified as a drought buster, but as DC said, every little bit helps.
If you click on the blue text of that NWS rainfall map above, with all the blues and greens, you may be able to figure out your total, more or less. There is one little finger of dark blue in SW Roanoke County that wd and I are in (dark blue translates to rainfall of at least 6/10ths up to 1 inch). Way down near the Blue and Red I-81 symbol in Washington County, there is an area of yellow. Right over Senor Hoback’s farm (I bet). The days of MH the RH are back. Congrats, Michael.
On closer inspection, wd, you might be in the light green area of 1 to 1.5 inches.
I am amazed that the NRV Link-Man has not yet posted the following, so I will try to be Postal Link-Man. The national Drought Monitor.
http://www.droughtmonitor.unl.edu The improvement in some of the states touching the Miss. River was not as pronounced as I expected. But most of Missouri is now at D2 or less, so that must be an improvement for that state.
Mike, thanks very much for posting the link to the national winds in your 11:18 AM comment. Kevin, Quags, Mike, joe, Xach, any of you other folks who know an awful lot about weather ….. please click on Mike’s link ASAP and tell us what on earth is happening in either eastern So. Dakota or NW Iowa. It reminds me of the black hole that was in that sci-fi movie by the same name about 20 years ago. GULP!!! Check that, it came out in 1979!! Maximilain Schell and Anthony Perkins.
What you’re seeing there, Doug, is the clash between cool, dry Canadian air and warm, moist Gulf air, with a low centered where you note. This is why there is a severe weather risk over much of the central Plains today.
That’s where that El Nino black hole is….
Can’t see what you are really talking about Doug. Only thing I can figure is dry air slot. There is a frame missing now.
Doug, thanks for picking up the drought map slack….it was a very busy day at work today…..not much computer time. The Drought maps are not perfectly accurate and certain spots will genuinely vary. My brother’s yard in far SW Mo only got 1.95″ out of Isaac and they moved him from the worst D4 to D2. Ain’t no way Jose. He’s probably a D3 now.
I did get another 0.15″ today. Beats nothing.
I see nothing unusual at all in Iowa ir Dakotas…just early fall jet max..if it was Nov id thinj itd be pushing snow squalls toward Green Bay…all i see is an early fall setup…..intl falls Minn…60f last hour…Vikes will see their breath soon.
Trevor in Cave Springs
Once Kevin mentions snow all the lurkers like me will overwhelm those who post year round! I still check in on the blog daily although I rarely comment unless flakes are going to be flying.
Blog numbers have been stronger this summer than any previously. The derecho had a lot to do with that. But I think lots of folks who are here a lot in winter are also drifting in and out through the summer.
The HPC put us in the dry hole for the next 5 days.
http://www.hpc.ncep.noaa.gov/qpf/p120i00.gif
Quags, I checked the wind map again, and the vortex in SD or Iowa is not nearly as pronounced as it was earlier this evening. KM explained it, I think. Probably a severe t-storm was a possibility there then, or maybe even a tornado? Or maybe neither. But it was quite a sight. Reminded me of water swirling madly just before it gets “flushed” down the hopper. Thanks for checking in about it guys.
As for you, Dryville Man (Rick), …. you are very welcome. Glad to hear you got a bit more rain. Have you clicked on the NWS rainfall map above? I hope that you are in the area either due south of Wytheville or a bit SE. The SW corner of Wythe and much of Smyth are two of the driest areas on the entire map. Like I was a couple of weeks or so ago on an earlier rainfall map.
Glad to see you commenting again, Todd. Seriously.
Quags, when are you going to give your preliminary winter analysis? Kevin, you usually dont put yours out until about Halloween, correct? Ready to turn the page on summer and move through fall into the winter! Think I love winter so much because in my industry its the only time of year you have a chance to catch your breath! Although up here they will play golf year around weather permitting, especially last nonwinter when we averaged 50s and 60s!
Classic Blue Ridge jumper with the storms on Saturday if that map is correct, Rick.
Hey, KM, is there any chance of getting a snowfall map in winter after a widespread snowstorm? Now that would REALLY be fun to see. It would likely show the effects of elevation on how much folks within the same general area got. The President’s Day (OK the day before President’s Day) snowstorm of this past February might have revealed that.
The radar map I posted wouldn’t be as impressive after a winter snowfall because the variations are generally by tenths of an inch of moisture, not by an inch or more. We think of 6 inches of snow as a lot more than 3, but it’s only .30 inch of liquid.
NWS-Blacksburg posts some maps after the fact, based more on actual observations. There is one at the bottom of this summary from the Feb. 19 snowstorm of this past winter.
http://www.erh.noaa.gov/rnk/events/2012/Feb19_snow/summary.php
I’m still here too. I’ve read the blog and comments every day but am eagerly awaiting the first winter threat to witness this blog really hopping again.
Great map, KM. Sure enough, SW Roanoke County (like my house) got 8 inches of snow (until the sun went to work on it big time!!), but a couple of my fellow postal employees who live in the city said they only got 6.
Gosh, I wish I could say more, but it is NFB (“Not For Blog”), a G-rated entity.
Jared, you and a few others have said recently that you are ready for autumn to begin. Count me in. I have not seen a temp below 68 yet at my house this month, I am pretty sure. Been above 70 for at least the last 4 mornings. Lowest temp at RRA this month is 70. This is September?
Speaking of Sept., both the 6-10 day and 8-14 day CPC outlooks are showing this region likely to be dry. Sorry, I am too lazy to post the links.
Doug, I’m just a 1/2 mile west of your favorite Wytheville Country Club course.
For snow in the U.S. right now — you have to go to Alaska. Snow level dropping to 1500 feet north of Fairbanks by Friday morning.
http://pafg.arh.noaa.gov/zonefcst.php?zone=AKZ220
Jared…
still working on it. I’ve set Sept. 22 as my deadline for my inital stab at winter. Still working on the data. Check back later…
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