3/28/04: FCST: Michigan and Ohio

SPC moved the slight risk back, inlcuding very little of MI. I believe that most of the storms will be in IN...particularly around the South Bend/IWX county warning area around 21Z-03Z this evening (agreeing with Rob). Low clouds have scoured out in that region, so temps should hit the upper 60's to near 70F resulting in some moderate instability, combined with good wind fields, and the cold front coming through, should be a couple decent storms.
Wouldn't expect anything farther east than that, it will be getting late and with the loss of daytime heating, what little instability exists will quickly diminish.


Robert
 
So it is morning now, and how do things look? ATTM, there are storms
moving through MO. Vis sat shows clear skies over most of central IL
and 80% of IN. However, a cloud band just west of the state line
doesn't appear to be going anywhere, and that will inhibit daytime
heating in the orginial target area. KIKK reports 70/59 right now
with broken clouds, KLAF 68/56 and clear, KCMI 66/56 and overcast.
The line of storms crossing into IL are not moving to the east very
much, but a quick look at the 925mb obs from DVN and ILX might
explain that. 40-45kts out of the SSW. However, the winds shift
rapidly as you look westward, so I don't think it will be stopped for
very long.

Eta shows slightly veering winds over the area at 18Z, with a tad
more veerage up to 850mb east of the state line at 0Z. NGM is a bit
more pleasing with the shear profile, giving veering winds through
700mb. Lifteds are in the -1 to -2 range across the target area for
the entired period. RUC shows strong Tds all afternoon stretching
from east of STL thur CMI and into the GRR area and central
Michigan. RUC also shows a CAPE axis of precisely sh!t heading
through the target area between 21Z and 0Z. Respectable helicities,
but a bit further west than originally anticipated.

EDITED: Well, I was going to head out, but all of my posse bailed and I'm not too excited about the prospect of driving 2 1/2 - 3 hours to chase a squall line with cells moving 50-70mph. Oh well, maybe next time. :(
 
72 degrees and 59 dt here at Kentland just before noon. Partly sunny now and cloudiness moving in per satellite from the west. Think this will definitely be an isolated low topped sort of event in my area later this afternoon and evening with wind and locally heavy rain being the main threat. We did get warmer than I expected with clear skies this a.m. but CAPE still negligible.
 
Severe weather threat looks like it is increasing across southwest lower MI and especially northwestern IN. Latest analysis from CAPS suggests that MUCAPE of 1500j/kg is overspreading a region from central IL northeast into northern IN, with LI down to -2C to -4C. Temps are higher than expected, with metar data showing low to even mid 70's with dewpoints around 60F, which is resulting in the mentioned instability. Directional shear across the region of best instability is weakening, with mainly a unidirectional profile, but speed shear is still very good, so any existing threat of supercells is quickly diminishing. If some storms can manage to develop along the warm front in northern IN/southwestern MI, where helicity is maximized, expect a slight increase in the tornado threat/low topped supercell threat...as discussed well by NWS GRR.


Robert
 
"If some storms can manage to develop along the warm front in northern IN/southwestern MI, where helicity is maximized"

As of 18Z I'm analyzing the warm front through most of SW Mich and clearly out of Indiana... All good helicity is moving away. While CAPEs are good, there's nothing to kick off anything. So by the time the forcing arrives late tonight, sunset will remove our instability. Nothing worth chasing.
 
Decided to make a forecast graphic, and see how it verifies later -

[Broken External Image]:http://www.waveformpc.com/outlook.GIF

I believe SPC is too far north and west with their outlook. I am speaking of severe weather in general, not necessarily chaseable storms (though those would be really nice!)...

StormTrack should make a thread where people can post their own forecast graphics such as this.

Robert
 
I was helping nowcast for Fabian Guerra who was south of Chicago on I-55. Some instability was there (clear most of the day), T/Tds were decent ahead of the precip, we had the front for lift. Cu was starting to become widespread across the area - it just never decided to get going. I think the only CG activity in this area was in a couple of small cells north of Chicago.
 
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