• Stormtrack's forum runs on Xenforo forum software, which will be undergoing a major update the evening of Wednesday, Feb 28th. The site may be down for a period while that update takes place.

10/21/04 FCST: Upper Midwest

12Z GFS shows dynamic upper level disturbance sweeping into the northern plains and upper midwest on Thursday. Strong wind fields and potent instabilities suggest convection is likely if this run verifies.
 
No, I meant for Wednesday...lol. I put this in the wrong thread, I suppose.

(My post was a little regionally biased, but what can I say? I can't chase the northern plains in the fall! :p )

In terms of kinematics, Thursday looks downright ridiculous for the upper midwest, though. I can't believe the 850 wind forecast. 50 kt low level jet over 6 states? You gotta be kidding me. To me, Illinois looks primed for a very nasty severe event, if the GFS verifies.

Gabe
 
GFS lost consistancy at the 00Z run, but looks like it's coming back closer to the previous solution on the 06Z run. The other medium range models are strong to very strong with this system, the strongest being the 00Z UKMET, dropping the low to 975mb, Canadian GEM shows a fairly strong low as well... So, even with the "blip" in the GFS, I would still give the event a 60%-70% chance of occuring (of course, just pulling that number out of a hat LOL).
 
ETA starting to catch onto the idea of some pretty good action THU - Though I do think the area of this thread should be expanded to include southern areas such as TX (where the dryline appears to be retreating with >70 to 75F td's on the ETA).

Strong mid and upper level winds in excess of 100-120knts, good upper level divergence, strong low and mid level baroclinic zones/temperature gradient, and 500mb trough becoming neutral to negatively tilted all favor rapid intensification of the SFC low in the Plains/northern Plains, at least on the current ETA. Moisture return has already began in the south, which will make it easier for the system to draw this even further northward into the lower MS Valley. Setup appears quite favorable for a classic fall severe weather event lasting 24-48 hours (of course with a nighttime lull)

Another thread may be needed for FRI from the Great Lakes stretching through the OH Valley region, as the low really beings to deepen (hopefully, LOL), but we are talking a good 5-7 days away still...
 
NWS offices REALLY playing this event up... Check this out from NWS GRR - They are expecting an event possibly rivaling October 24, 2001!! :shock:

THE FRIDAY INTO SATURDAY TIME FRAME COULD BE A SIGNIFICANT SEVERE
WEATHER DAY FOR SOUTHWEST MICHIGAN...THINK OF OCTOBER 24 2001.
 
Originally posted by Dan Cook
DVN's mentioning an \"active day\" for Thurs.

Yeah, NWS offices are really playing this one. GRR is saying temps may hit the low 80's late in this week, which here in MI has only happened 5 times since 1900, all on the same day... Also saying moisture will be abundant... PWat values will be a solid 3-4 times climatological values - GRR and DTX say that PWat records could very well be set.

So, barring any significant changes in models - Instability/moisture will definately be there (if temps push 80F, thats warmer than the 10/24/2001 event), and deep layer shear is in excess of 70knts - It would be close to a perfect setup for our region (i.e. Midwest/Great Lakes, Ohio Valley).
 
Maybe noone has looked at last night's GFS, but indications are that the main upper wave will not eject until Friday, not Thursday, so there may not be much forcing around for convection on Thursday to get excited about. Strong jet dynamics are forecast to promote some convection in the northern plains, where moisture will be limited. That said, always a chance of a smaller scale feature that won't be resolvable until the lead time shortens substantially that might make things happen elsewhere as ample moisture and instability should be surging up the Miss. River valley - but probably will remain capped to surface convection (though elevated warm air advection precip might lead the warm front across the upper Great Lakes). If this trend continues, I'll start a new thread for Friday if one doesn't already exist after a few more run cycles.

Glen
 
Originally posted by Glen Romine
Maybe noone has looked at last night's GFS, but indications are that the main upper wave will not eject until Friday, not Thursday, so there may not be much forcing around for convection on Thursday to get excited about. Strong jet dynamics are forecast to promote some convection in the northern plains, where moisture will be limited. That said, always a chance of a smaller scale feature that won't be resolvable until the lead time shortens substantially that might make things happen elsewhere as ample moisture and instability should be surging up the Miss. River valley - but probably will remain capped to surface convection (though elevated warm air advection precip might lead the warm front across the upper Great Lakes). If this trend continues, I'll start a new thread for Friday if one doesn't already exist after a few more run cycles.

Glen

I was talking mainly about FRI, though a thread doesn't exist, but I believe it will be a 2-day type of event - THU being in the Plains, spreading ENE'ward into the MS Valley/OH Valley/Great Lakes ...

As you said, I noticed this trend on the 00Z models, and actually looking at all of the latest data (12Z ETA), it looks like the event could be even further delayed, since models usually eject these low too fast anyways...

So... What do I actually think? I think this thread should be changed to "10/21/2004: Plains" with a new thread "10/22/2004: Midwest/Ohio Valley"... Which would be appropriate until the event changes schedules, again, LOL...
 
Or even 10-22 Plains, 10-23 Ohio Valley(if not plains again....lol). ETA says not plains 10-21. I wonder how the gfs is going to bring this out now beyond 84hr. ETA looks like it'd come out rather pos tilt. Can't believe the difference in the dewpoint progs now, though I should.

Ok, who tripped over ncep's power cord? Could someone please plug that 33mghz puter back in? Damn, don't they know we need to see things 108hrs away RIGHT NOW????
 
If I could pick which model I would want to be correct, I would pick the ETA...

At 84hrs, it's stronger than the GFS, and seems to keep most of the energy (at 500mb) consolidated into a single system, rather than the GFS which has multiple weaker systems... ETA does look positively titled at first, but I believe if there was an extension to the 84hrs (lets say out to 108hrs or so or TRUE ETA (no GFS extension)), it would soon go negative...

Like I said, GFS seems to split up the shortwave into a number of weaker systems as opposed to one large system, which is what the ETA looks like it wants to do...
 
ETA does look positively titled at first, but I believe if there was an extension to the 84hrs (lets say out to 108hrs or so or TRUE ETA (no GFS extension)), it would soon go negative...

See how at 84hr all the wind energy is on the east side of the trough? It seems as though when that happens they tend to come out positive tilt(via my very low experience in looking at models). That or a small distubance comes out posibly more negatively tilted(like the gfs WAS showing...ain't looked yet at what new gfs says). I could almost see the eta going that route and leaving a trough in the west...well, it looks to stay troughy anyway. I'd just rather see some better winds diving down the back side of the trough as it moves east(or at the 84hr time frame on the eta).
 
Latest NWS discussions across the MS Valley and Ohio Valley concerning the even (THU through FRI timeframe) are less than impressive this go around. Not even a mention of severe from MKX, GRR, DTX, IWX, etc... DTX does say that it is possible the low could just sit and spin in the southwest (since the jet on the backside of the system is stronger than what models are indicating, that means it could dig even deeper than expected), and not even eject for quite some time (i.e. a cutoff low that will just sit there and weaken)... Only time will tell...
 
FWIW, there is a general bias for models to move troughs out of the western/southwestern US too quickly. And indeed, we've seen this again with the GFS as the last-week Wednesday target has now moved to MAYBE Thursday and more likely at least Friday. I'd be weary about examining model specifics this far out, and this general west-coast trough (and associated southwest flow aloft in the central US) climatologically favors severe weather events. Of course, the low-level fields are still to-be determined, and it are these low-level fields (moisture, shear, etc) that I think will make or break the possible event when the main system does eventually come out. IF we can get >mid-60 Tds westward to atleast the central OK/KS/NE area, I think there will be SOME significant severe weather associated with this system, but whether it's in the plains or east of there is still up in the air.
 
FWIW, there is a general bias for models to move troughs out of the western/southwestern US too quickly. And indeed, we've seen this again with the GFS as the last-week Wednesday target has now moved to MAYBE Thursday and more likely at least Friday. I'd be weary about examining model specifics this far out, and this general west-coast trough (and associated southwest flow aloft in the central US) climatologically favors severe weather events. Of course, the low-level fields are still to-be determined, and it are these low-level fields (moisture, shear, etc) that I think will make or break the possible event when the main system does eventually come out. IF we can get >mid-60 Tds westward to atleast the central OK/KS/NE area, I think there will be SOME significant severe weather associated with this system, but whether it's in the plains or east of there is still up in the air.

It's hard to do, but I am not gonna look at a single model until WED or early THU, and see what has become of the situation. I believe there is a "law" out there, something about a watched pot never boils... Well, I'm gonna close my eyes to the models, and things better start boiling, LOL...
 
Back
Top