Thursday is looking like a potential chase day around the area. Since I'm on a fairly short leash regarding money and mileage on my car with my up-coming vacation, this seems to shaping up quite well.
Granted this is a few days out yet, but the 00z NAM and GFS, as well as the 06z NAM are staying rather consistent. The 06zNAM is indicating plenty of shear (200+ helicities over much of Ern ND) and instability (EHI's of 2+ over SErn ND) for big storms. Flow is respectable with a nice 70-90 KT westerly jetlet at 500mb above southeasterly flow at the surface. The resultant hodographs are simply amazing with all kinds of curvature and storm-relative inflow...
It's something I'm certainly going to be keeping an eye on. If things remain consistent, I may just take the opportunity to finally make it out again. After an active two weeks at the beginning of the month, we've fell back into a lull the two weeks since. Yesterday's setup was very marginal and things pretty much happened the way I figured it would - not firing up until after dark, at least in and around the Nrn Valley area.
Let's hope Thursday pans out!
Stay tuned...
We may be looking at another opportunity to chase tomorrow. Looking at the latest models, much of central and eastern North Dakota may just be looking at a decent threat for Supercells and tornadoes. Low-level and deep-layer shear and instability look outstanding and our mid and upper-level flow is more than enough to support Supercells.
I haven't seen hodographs like these in quite some time, so I feel I need to share these... This image is a forecast sounding near Grand Forks, ND at 3Z Friday (10:00pm Thursday evening). The hodograph in the upper-right hand corner is one of the largest I've seen in quite a while. That is some outstanding storm-relative inflow!
Capping won't be as much of an issue as with our chase days over the past week and if the trends continue on the NAM, convection may fire late in the afternoon and that would certainly help my cause. Since I'm on mids this week, I'll have Thursday open, but I'll have to be back into town by 11:30pm Thursday night for work.
It doesn't look like I'd need to drive far and that will help, as well.
This definitely looks like one of the better setups we've had around these parts in some time.
I'll continue to watch things over the next day or so and will try to update the blog here.
More later...
It's looking like my plans for my extended time off this weekend from work will be changing somewhat. I was initially thinking of taking a road trip out west to finally see the badlands here in North Dakota.
It's looking now, that while I'll still be heading west on Saturday, it will be to see Supercells! This afternoon's 12z NAM is indicating a fairly significant surface trough pushing eastward across the Northern Plains. Steepening lapse rates and good flow in the mid to upper-levels should give us plenty of instability and shear for Supercells. I'm a little concerned with the mid-level temperatures. With 700mb temps from 10 to 15° C, it will be fairly capped out there. The NAM is convecting things over western/central ND between 21 and 00z, which I think is being quite liberal. I wouldn't be surprised if things hold off closer to sunset. It does show some slight weakening in the inversion along and just behind the frontal boundary, so maybe ascent will be strong enough to provide that trigger to bust through it.
It's a couple of days out yet, but it will be something I'll keep close tabs on over the next 24-36 hours.
I'm definitely enjoying this pattern...
Looks like this week may be the first real opportunity to get out chasing across the state. Tomorrow could be active across the western part of the state with Thursday looking like another active severe weather day.
I'll be monitoring things closely tonight and may decide to head out west tomorrow to check things out. Depends on dynamite of a setup it turns into overnight tonight on the models and how much sleep I want tomorrow. Otherwise, I may just wait it out until Thursday's event.
Stay tuned...
The models over the past week had been hinting at a day or two in the 60's to 70's yesterday and today. While yesterday we didn't exactly hit the 60° mark, the airport recorded a high of 59° while here in town at the NWS office, 52° was recorded.
Today could be a different story. The NAM/GFS/GEM consensus has us, at least, hitting 70 degrees, with the GEM warmest, having us into the upper 70's.
Output from the NAM and GEM, respectively, follows - indicating their respective maximum 2m Temperature forecasts for this afternoon:
Light snow continues to spread over much of the Ohio Valley this afternoon ahead of a fairly potent low pressure system. Winter Storm Warnings continue and it also continues to appear that significant snowfall accumulations are eminent over the northern half of the Hoosier state through tomorrow evening.
Here is what our afternoon forecast for IN-DOT is indicating for total snowfall accumulations. This is valid for the 1:00pm Saturday through 1:00pm Sunday 24 hour period.
Winter Storm and Heavy Snow Warnings have been issued for much of the Ohio Valley today and are valid from this afternoon through most of Sunday.
It appears that most of Indiana and Ohio will see significant snowfall with this system, with northern areas seeing the heaviest accumulations. While computer models differ some on their precipitation forecasts, the most aggressive (the NAM, or North American-Mesoscale) model is painting quite the picture for parts of Indiana:
The image below indicates that heavy snow will begin late tonight over western parts of Indiana, then spreading northeastward during the overnight and into early Sunday morning. The image below shows a maximum accumulation of liquid of 0.989, which assuming a 10:1 ratio, would amount to near 10 inches of snow, but paints most of northern Indiana over 0.75 or 7-8 inches of snow by 12Z on Sunday. This is equivalent to 7:00am EST. Note, this also only indicates snowfall during the previous 6 hours - so this is 7-8 inches within a 1:00am to 7:00am period. Nearly an inch per hour! If that would actually occur, that's pretty impressive!
This next image from 18Z, or 1:00pm EST shows the next 6-hr period and indicates another 5 to 8 inches over north-central and northeastern Indiana. This would bring a total accumulation from 12 to 16 inches of snow!
And finally, the last 6 hours of the event, for the most part, indicates only light accumulations (generally an inch or less) associated with lighter snow and flurries through 00Z Monday, or 7:00pm EST, Sunday evening.
Things should be much quieter by this time, but I'm sure all you Hoosiers will all see a much whiter world tomorrow!
If you are reading this from Indiana and would happen to snap any photos of this snow event, please pass them along! I'd love to see how things pan out. While I don't exactly feel that 17-18 inches will fall, I'm confident enough to say that a 12 inch accumulation will be likely, somewhere, and that there is a possibility that there could be some local spots of slightly higher accumulations.
My personal snowfall forecast would sound something along these lines...
+ Locations north of a line from Crawfordsville to Portland: 8-12 inches (slightly higher, locally)
+ Locations south of this line and north of a line from Terre Haute through the south-side of Indy to Richmond: 4-8 inches
+ Locations south of this line and north of a line from Vincennes to Lawrenceburg: 1- 4 inches of snow with light ice (freezing rain or sleet) accumulations possible
+ Points southward: an inch or two, with ice accumulations up to a quarter-inch also possible Sunday afternoon
Now this just sucks...
For those of you that don't typically look at numerical guidance, this is indicating areas of light snow across portions of North Dakota Saturday. Granted, it likely won't amount to anything (soil temperatures are still quite mild) but any snowfall is snowfall I'm not prepared for! I'd much rather skip over the next 5 months and go right into spring and early-summer. ;)
We've been watching today for the last few days via the GFS and NAM, and it appears that there is still a good chance for storms this afternoon and into this evening across much of eastern North Dakota. With the weekend off, my chase status is pretty much a go. I've come into the office to look at things a little more closely and Turcotte will be joining me shortly. We've decided to rendezvous here to straighten out logistics for the afternoon.
I'm still leaning on my initial target area; around the Cooperstown area. Any area from Cooperstown, to Valley City, to Crookston (MN), to Detroit Lakes (MN) looks good, though - particularly over the western and northern portion of that area. The warm front is hanging up in that region right now and I'm not sure how much further north it's going to surge. If it can hang around there, backing winds along the boundary will result in a much greater sheared environment for rotating storms.
Impressive to see LI's at -12 and lower and CAPE values nearing 7000 (wow!) near the Jamestown and Valley City area towards 00z on the 18z RUC. I'm not quite buying into that, but it's still impressive!
Will likely be taking off here within the next hour or two.
It's looking like today may turn into another chase opportunity for us here in the Northern Plains. We're sitting under a fairly extensive cloud deck this morning over much of eastern North Dakota, however we should see some clearing this afternoon and with us getting into the warm sector of the shortwave pushing east-northeast through the region today, we should get into some decent instability. The 06z NAM and GEM are a bit quicker and start convecting around 21z over eastern areas of North Dakota and then progressively initiate thunderstorms along the inverted trough axis and cold front this evening. The NAM still seems a bit high on it's moisture return this afternoon, with surface dewpoints increasing into the mid 60's across the area by this afternoon. I'm a little concerned with that, given that our dewpoints this morning are only in the lower 40's across the northern valley. They are increasing over the southern portions of the valley down by Fargo (they've gone from 38° to 52° in the last 2 hours) and especially near Wahpeton (from 53° to 61° over the same period) where they're getting sun already.
The quicker we lose these clouds, the better chance for our daytime heating and moisture return. LI's range from -2 to -8 across the region and with EHI's at 3+, it seems that we have a decent balance of instability and shear. Could very well have some supercells out there this afternoon. Looks like east-central parts will be prime by later this afternoon and if I do head out, I'm thinking of heading in that direction.
More later...
After consulting with the 06z runs this morning before leaving work, it seems that both the WRF and GFS are slowing the system down even further. They both begin convecting towards 18z over north-central portions of the state (which isn't a surprise given the weak capping) but still hint at that pre-frontal trough developing over east-central portions of the state later this afternoon. I'm still hoping for development of additional discrete storms along this corridor (from Devils Lake through Carrington, down towards Medina). The 06z runs still indicate enhanced EHI values and fairly strong signals for H85 Theta-E advection between 18 and 21z. I am adjusting the target area a bit further north and west - near New Rockford, ND. Highway 281 will give me a good north-south option and since the WRF does indicate slightly better forcing west of the Devils Lake basin it would make better sense adjusting northward some.
If things don't develop in the higher instability and along the pre-frontal trough (if that indeed develops) then I'll, at least, be in decent shape for a nice squall line to push through during the late-afternoon and early-evening.
The plan right now is to head into work around noon today, to get the latest data, make a decision and to call co-workers Brad Werner and possibly Bryan McQuade to see if they would be interested in riding along. Having a partner or two would be really nice to make the gas a little cheaper. Then to head out around 2:00 or 3:00pm CDT towards New Rockford.
Will update more once I get to work later...
Models have been fairly consistent with this shortwave pushing eastward across the Northern Plains and this may turn into my first official chase for the 2007 season. The last couple of WRF and GFS runs have slowed the system down some and wants to fire off convection over the Devils Lake basin, however still hints at a pre-frontal trough with a coincident wave pushing north-northeast out of South Dakota during the afternoon.
I'm hoping that this may lead to development a bit further east, where 850 Theta-E advection is fairly strong and sets up a decent tongue by 21z.
The synoptic setup is still impressive with plenty of shear to go around... Deep layer shear is more than sufficient for large hail and high winds and with low-level shear at this magnitude I could see possible tornadic storms out there somewhere. I really like the EHI's by 18 and 21z.
Right now, I'm planning to catch up on model data early tomorrow, make adjustments to the target area, meet up with potential chase partners, and head out.
Right now, I'm thinking of near Carrington to possibly Cooperstown...
More later!