3/28/04: FCST: Michigan and Ohio

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Severe weather does look possible Sunday, but wouldn't get too excited just yet. System will likely have decent jet dynamics/veering in the lowest 0-3km based on 12Z ETA, but as with most synoptic systems this early in the season and this far north, instability is the key question.

Here is a paragraph from the NWS DTX AFD:
SUNDAY...
THETA-E RIDGE AXIS IS OVERHEAD WITH FIRST WAVE ASSOCIATED WITH THE
WARM FRONT LIFTING NORTH. WHERE THIS WARM FRONT FINALLY SETS UP
WILL DICTATE A LOT WHAT HAPPENS LATER IN THE PERIOD. WITH INFLUX OF
MOISTURE WE WILL NEED TO CARRY SCATTERED SHOWERS. ELEVATED
INSTABILITY WITH SWI/S AROUND 0C WOULD SUPPORT OUR CHANCES FOR
THUNDER. IF WE ARE ABLE TO GET THIS WARM FRONT FAR ENOUGH NORTH,
LATE SUNDAY COULD BECOME INTERESTING WITH MODIFIED PARCELS
SUGGESTING CAPES CLIMBING TOWARD 1000 J/KG WITH SURFACE BASED LI/S
BELOW 0C. AGAIN, PLENTY OF TIME TO MONITOR!
DTX also goes on to mention that a line of storms Sunday Eve/night is likely, but do not mention severe or even strong storms...But the event is still a couple days out.

Robert
 

Dan Robinson

Moisture is also painfully lacking in the warm sector, at least today. Dewpoints in the low 40s seem to be pretty widespread. Looking at the surface charts, there doesn't seem to be a whole lot upstream advecting north either, so I'm not sure how much this will improve by Sunday.

With the high temps and low DPs, If we don't get any precip here tonight, there could be a fire danger scenario taking shape in the Appalachians this weekend. Happens every year about this time.
 
Still appears to be a narrow possibility of severe thunderstorms tomorrow evening across areas from western lower MI southward into IN. Event will really depend on the amount of low level heating, moisture return, and associated instability. If strong SFC based convection could develop, there is plenty of directional and speed shear, with 0-3km helicity of over 400m2/s2, and the threat for severe thunderstorms would increase quite a bit. The more likely scenario is that clouds will hang around, like the past few days, and cause temperatures to remain around 60F. If this second scenario were to occur, still expect an isolated severe thunderstorm or two over southwest lower MI and western IN associated with some sort of pre-frontal squall line.


Robert
 

Joe Smith

Robert, I think your assessment is accurate regarding storms in In. and Michigan. The key item seems to be the amount if any clearing we have tomorrow in our general area. Seems to be a linear event in my area but your progged helicity values are interesting. Plan to head over to the Monon Indiana area tomorrow afternoon to join a friend to see what might develop. Good moisture and shearing but the key this early is always instability. Still, there have been major tornadoes like the Tri-State with temps in the 60's along the track.
 
Originally posted by rdale
I don't see anything other than some gusty winds will 'squall line' passage...
I tend to agree with Rob. I'm not seeing much in the way of directional shear, and the CAPE values look pretty low. Decent instability though. Still, I doubt it will be enough to convince me to buy a tank of gas. I'm awaiting the 0Z model runs and the 6Z SWODY1, but I don't expect to find too much different.


Ben
 
Originally posted by Ben Cotton
I tend to agree with Rob. I'm not seeing much in the way of directional shear, and the CAPE values look pretty low. Decent instability though. Still, I doubt it will be enough to convince me to buy a tank of gas. I'm awaiting the 0Z model runs and the 6Z SWODY1, but I don't expect to find too much different.


Ben
It appears as though directional shear in the lowest 0-3km is decent, across lower MI anyway. Further south and west, helicity drops off pretty fast, which may be where you were looking. I believe this is because SFC winds are from the southeast, veering towards the southwest at around 850/700mb, which creates around 70 degrees of veering in the lowest 0-3km. Above that layer, directional shear is non-existant. Storms will be highly dependant on the amout of SFC heating and associated SFC based instability, so I'm not going to say absolutely no severe storms, since conditions could change. As my original post stated, I believe that an isolated severe storm or two is possible, and the NWS discussions seem to verify this, but I agree with you that it wouldn't be worth a tank of gas.

Robert
 
This is for IL/IN but it's close enough. I don't think MI/OH will get anything before dark anyway....

This is not the best setup ever, but it's still March, so I'm not too displeased. The way I see it right now, timing is going to be the biggest concern. Will the storms and the setup be in the right place relative to eachother. 18Z looks to have decent goings on in central IL, but the Eta and NGM both prog the precip to be west of the instability axis. By 0Z, the best conditions will be found along the IN/IL state line, but the precip will only be just getting there. The shear profile looks markedly better than the 12Z runs were suggesting, which is encouraging. I could definitely use some more CAPE though. I think the best chance for excitement will be around the state line between 23Z-1Z. I'm going to sleep on it and see what the 12Z upper air obs and model runs look like, but if I go out I'll probably start near Momence or Kankakee and work my way east with the storms. Maybe the line will throw out some outflow boundaries to kick off some isolated stuff ahead. Probably not, but a guy can hope.


Ben
 

rdale

EF5
Mar 1, 2004
7,226
776
21
50
Lansing, MI
skywatch.org
I like the clearing in northern IL but I'm still nowhere near as excited as SPC / NWS GRR. Nothing like our typical March events though!

Anyone know why GRR thinks tonight's storms in SW Mich will be elevated?

- Rob
 
Dec 9, 2003
573
3
5
Colorado Springs, CO
Almost seems like GRR is expecting some really good heating this afternoon, they're expecting some increase stability. I'm not sure, it's overcast here in Big Rapids. If there is good clearing with the temps getting in the mid 60's to 70 I could see it, but my saying that tends to nix any chance we might have. I'm contemplating heading downstate this afternoon. I'd like to see it happen, if it does, later in the afternoon.

Tim
 
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. :(
 

Joe Smith

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
 

rdale

EF5
Mar 1, 2004
7,226
776
21
50
Lansing, MI
skywatch.org
"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