#vawx A blast from the past but not much hope for the present

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Twelve years ago today the remnants of Hurricane Ivan spawned a tornado outbreak in Virginia. I was fortunate enough to witness this one that was evaluated as an F-3, damaging houses in the Remington VA area.0e34c-17sep_chase00528229

NWS Sterling issued a tornado warning on this cell within 3 minutes of our storm report.

So will there be anything to chase tomorrow (9/18/16)? At the moment it doesn’t look like anything much will fire east of the mountains. The surface front isn’t very progressive per this morning’s model runs and the upper levels look pretty warm atop the Piedmont (i.e. convective cap is strong). We’ll see…

#vawx Chasing hopes are now focused on Sunday

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A somewhat rare numerical model role switch is underway at the moment. Regarding Sunday’s (9/18) chasing potential the GFS is actually more bullish than the NAM. Here’s the GFS sounding for Bedford county that afternoon at 21Z (5 pm EDT) from this morning’s model run:12_gfs_081_37-35-79-89_severe_ml

Although this isn’t a ballistic setup these instability parameters are significantly stronger than the NAM is showing. With somewhat decent shear values this may mean that I haul out the chase gear Sunday afternoon.

The difference seems to lie in how each model handles the approaching cold front. The GFS shows the boundary well east of the mountains by nightfall while the NAM wants to slow down the frontal passage. Both models handle the associated upper level trough pretty similarly.

Regardless, I have my eyes on Sunday afternoon and will be watching the short range models closely as they come into play. I could use another chase (or two) before the season shuts down!

#vawx Opportunities are dwindling quickly

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September is very much a hit-or-miss month for chasing storms in the Old Dominion. Cold fronts – if timed right – can bring one or two opportunities, typically shelf cloud producers vs. mesocyclones (rotating updrafts). The main hope for the latter this time of year is tropical remnants rolling across the state which can produce low-topped supercells.

Hermine didn’t comply as it stayed well offshore (fortunately for folks along the coast!). And at the moment there don’t appear to be any other tropical systems coming along that could fill the bill. Thus we’re down to watching and waiting as cold fronts begin their autumnal march across the country.

At the moment the next such setup looks to occur Friday of this week as a boundary crosses Virginia. Forecast CAPE (instability) and shear values are both rather low so it may not even be worth considering. Next week, however, a cold front with better upper level support may bring a chance for decent chasing.

Here’s a depiction of the supercell composite parameter for late Wednesday afternoon. Admittedly this is an off-hour (06Z) GFS run and it’s pretty far out (207 hours) to trust in details:GFSMA_con_scp_207

Nevertheless both the CAPE and shear look decent. If this timing is correct I should be able to chase that afternoon. That’s important because September’s schedule is very full of non-chasing activities.

The 2016 Virginia storm chase season is quickly winding down.

#vawx A very uninspiring chase to begin meteorological fall

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Yesterday’s chase was so uninspiring that (a) it took me until today to write it up and (b) I’m not even posting any photos here.

A cold front was forecast to bulldoze the heat and humidity out of the region Thursday. The shear associated with it convinced me to give chase. (During the late summer I tend to grow weary of chasing high CAPE / low shear setups with “whack-a-mole” storms that pop up and rain out quickly.)

The main problem with the setup centered on the early timing of the front and convection firing out ahead of it. Thus I left home around 11:15 for Bedford to stay ahead of a northeast/southwest oriented convective line. But before I reached Bedford a couple of nice discrete storms erupted along the U.S. Route 29 corridor near Danville, well ahead of the line itself.

These – of course! – were the storms of the day, showing radar-indicated midlevel rotation even before the noon hour. There was no way I could reach them as I’d have been in a futile tail chase. Frustrated at this development I wandered around south of Bedford keeping an eye on a fairly intense line segment rolling across the Roanoke valley.

I decided to intercept the southern end of this segment and crawled south thru traffic across Smith Mountain Lake to a point where I could see a blurry shelf cloud approaching from the west. I switched on the live feed for a while from this location.

However the line weakened considerably as it crossed the Blue Ridge. When the rain neared I continued south to the VA Route 40 corridor to stay ahead of it. To shorten a boring story I finished the chase east of Gretna watching as the line diffused into a general rain maker. I saw no lightning, felt a little outflow breeze, and that was about it.

So not quite a bust but not much better than one either.

#vawx “Mystery” solved

Mystery from last night solved. The two features circled in orange on this graphic are upper level (250 mb) closed lows:wv sat image

Via the 06Z GFS run here’s the one just south of Charleston SC:GFSSE_250_spd_000.jpg

And here’s a very unusual upper low southeast of Florida out over the Atlantic:upper low GFS

I was too weary last night to figure this out. Kudos to Kevin Myatt who guessed this to be the case in his answer to my late evening question.

Now, here’s hoping there will be sufficient convective activity during this week’s cold front passage to warrant a chase. It’s a faint hope but I’m sticking to it.

#vawx A tropical mystery

This is hurting my brain tonight. First, here’s the latest National Hurricane Center two day tropical outlook:two_atl_2d0I understand this graphic.

Now, here’s a current water vapor satellite view:wv sat image

When this view is looped the features circled in orange are spinning counter-clockwise like mad yet aren’t labeled as anything on the NHC graphic. So what are they?

It’s a mystery…and it’s late enough that I’m heading to bed without trying to solve it. I’ll check it out in the morning.

#vawx A tropical remnant chase to start September?

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With the Atlantic tropical basin coming alive there’s hope for a storm chase of tropical remnants here in the Old Dominion. At the moment Fiona and Gaston both look like they’ll steer clear of the U.S. mainland. However the third system – to be Hermine if it develops – may be a factor.

Here’s the current 7 day WPC forecast map.9nhwbg_conus

“Hermine” is the low pressure just off the west coast of Florida. The orange arrow I’ve added shows the 10 day Euro model forecast of its track. IF this path is correct (too far ahead to bet on) the southeastern states could be very wet and windy as September begins.

However this track doesn’t bode well for chasing convective activity here in Virginia. But if the storm’s path shifts and pushes northward along or just west of the Appalachians the beginning of meteorological autumn (Sept 1st) may provide an interesting chase opportunity.

We’ll see.

 

#vawx A welcome cold front with more shelf cloud action

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Although a strong cold front promised relief from the Mid-Atlantic heat and humidity it didn’t bring much shear with it. Thus today’s chase was yet another “shelfie-fest”with a squall line providing the outflow.

Heading out just after 1 pm today I rolled to Rocky Mount to refuel the chasemobile and choose whether to continue south on U.S. 220 or go east on VA Route 40. After reviewing radar I chose the latter as a squall line was taking on the typical southwest – northeast orientation associated with a cold front passage. This time tho’ I didn’t stop in Glade Hill but maneuvered south and west from there to a Franklin county hilltop.shelf from Franklin county vantage

When the shelf cloud began to fill the western horizon I continued east and south along more rural roads into Pittsylvania county. At this point the shelf was very close so I didn’t stick around long to watch:

As I pushed further east I stopped intermittently for short periods to observe the shelf at close hand with rain nipping at my heels:Right behind me

I wound up heading south on Virginia Route 41 toward Danville and then diverting east to U.S. 29 near Blairs. At this point the leading edge of the northern section of the line was east of Rte 29 while the southern section was dissipating. I did drop all the way south to U.S. 58 in Danville where I paused to grab a snack and evaluate the situation.

With little hope of anything more interesting to see (retreating in front of shelf clouds gets old after a couple hours) I called off the chase and headed home. It was an enjoyable and relaxing chase but I’m itching for something more. Unfortunately without tropical help this time of year doesn’t hold much more potential.

#vawx A shelf-y chase with a hint of mesocyclone

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Although conditions were similar to recent chases (lots of CAPE, little shear) today had some extra impetus in the form of a short wave crossing the mountains. With storms going up along the ridgelines to the south I motored down the driveway at 1:30 for Rocky Mount. Intending to stop there to evaluate things I instead turned east on VA Route 40.

At Glade Hill I rolled south and then east along rural routes to a hilltop vantage point for a peek at the convection. After switching on the live feed and watching for a while I realized the activity wasn’t pushing east as fast as I’d originally thought so I moved back west and then north to the Glade Hill vicinity. There one cell showed symptoms of a mesocyclone and accompanying wall cloud:

As this feature progressed northward I ventured in the same direction for a bit until it became obvious that (a) the rain was cutting off my forward path and (b) convection to the south was strengthening (it had become severe-warned). Thus I bailed on the northern complex and reversed direction, speeding south to Rte 40 and turning east.

I dithered some on how far east to travel before finally jumping onto the Museville Road and heading south. Just before reaching Callands I found a spot to pause and watch for several minutes as an impressive shelf cloud approached, grumbling with copious amounts of thunder:shelf cloud approaching Callands

When this leading edge neared the radar view suggested that I needed to vacate the premises or face possibly serious consequences:

Thus I finished the journey to Callands where I diverted east on VA Route 57. Finding a spot to – briefly – stop near Rondo I had this view of the shelf coming right at me over a tobacco patch:shelf cloud near Rondo

Instead of continuing to race in front of the line I chose to scoot south just in front of it all the way to VA Route 41. In doing so the leading edge of the shelf overtook me so I stopped to snap a couple of photos from inside the “whale’s mouth”:Whales mouth Pittsylvania county

I wound up going thru Dry Fork and stopping near U.S. Route 29 just north of White Oak Mountain. As the original storm faded and another one built on the outflow the resulting lightning output was fierce, close, and rapid enough that I kept my hands away from anything metal in the chasemobile. At one point the local TV station lost my live feed, due – I think – to a nearby cell tower being affected by the electrical discharges.

From here I ducked south on 29 over the mountain to scout out what features might be of interest for the 5 0’clock TV weather block. Once that block was over I called it a chase as the leading edge (and accompanying shelf cloud) was east of me and moving away.

A decent August chase if I do say so myself!

#vawx Not a bust, but a chase without a decent photo to show for it

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More “whack-a-mole” storms today. High CAPE (instability), no cap, and little shear allowed storms to go up early and rapidly and fall apart just as fast. The huge amount of water vapor in the air provides potential for flash flooding and that’s exactly what downtown Roanoke experienced today.

For several reasons I wasn’t prepared to chase early this afternoon but when thunder rattled the house I scrambled around gathering up gear. I headed down the driveway around 1:30 or so, barely ahead of the rain. Rolling north and then east I emerged onto U.S. Route 460 as heavy drops began to smack the windshield.

I desperately sought an open vantage point east of the highway in the Webster area but never found a clear sightline. Thus I repointed the chasemobile east on 460 and sped ahead of the action. After a couple of unsuccessful detours onto side roads to find an adequate view of the advancing complex I continued to Bedford and turned south on VA Route 122.

By this time a discrete cell on the eastern edge of the original action had gone severe-warned and looked like this on radar:IMG_5348Of course at this time I was also stuck in road construction, the bane of stormchasers everywhere. Finally extricating myself from the entangled mess I maneuvered via rural Bedford county roads to find a spot to watch the storm.

And by the time I did the radar view had degenerated into this diffuse blob:IMG_5349Note the second view is only 15 minutes after the first one, reemphasizing the need for wind shear to allow a storm to maintain its updraft. “What goes up must come down…quickly” in a low shear environment.

The leftover anvil from the original convection overspread the entire area and suppressed all potential activity for several hours. I called it quits and rolled home early. I did snap a few photos and even had the live feed up for a bit but none of the photos is even worth posting.

Maybe later this week we’ll have some shear from a weak front that is supposed to sag into Virginia and dissipate. Until then it’ll be “whack-a-mole” chasing at its finest.