March 15/16 Severe Wx

[RyanDe680]

Not sure if anyone's mentioned this yet anywhere else, but the sustained wind field on the 18z GFS is awesome.

 

sfcmw.png

 

Am I off my rocker when I say that with most low pressure systems lately (last year or so, below 995 lets say), the wind has been somewhat abnormal in strength?  It's just that it always seems like these low pressures are so wind wrapped lately that there are more wind advisories than in the past?

[RyanDe680]

From what I've seen, the Euro has even poorer moisture than the GFS.

 

Edit: And that doesn't look to change with the 12z run. It is just so flat, there is barely any amplification whatsoever.

 

And the Euro vs. GFS battle has been pretty one sided lately....

[andyhb]

Will be interesting to see the 12z EPS rolling out shortly.

 

Not much difference between the EPS and the operational.

[Stebo]

Not much difference between the EPS and the operational.

I'd say that there are more stronger lows on the EPS compared to the op at 108.

 

[HillsdaleMIWeather]

0Z GFS trended with more instability and a higher lapse rates further north. Looking like a large squall line could be thesible

[andyhb]

0Z GFS trended with more instability and a higher lapse rates further north. Looking like a large squall line could be thesible

 

Barely. Also the axis of instability is narrower, the trough occludes quicker and the wind profiles aren't as favorable. It's certainly a downtrend.

[andyhb]

Wow the 00z Euro is slowing pretty significantly. Also looks deeper with the surface low significantly farther south.

 

This would be the type of thing to pull a more significant event out of this potentially.

[cyclone77]

Wow the 00z Euro is slowing pretty significantly. Also looks deeper with the surface low significantly farther south.

 

This would be the type of thing to pull a more significant event out of this potentially.

 

Also showing 55-65mph gradient wind gust potential for Wed the 16th over northern IL and northern IN.

[ClicheVortex2014]

Wow the 00z Euro is slowing pretty significantly. Also looks deeper with the surface low significantly farther south.

 

This would be the type of thing to pull a more significant event out of this potentially.

It slowed down, but it doesn't look like it budged much with the amount of CAPE. 

[Stebo]

It slowed down, but it doesn't look like it budged much with the amount of CAPE. 

It won't take much of a bump up to make this a significant event. Just a tick up in moisture return is all we need, we have the lapse rates and wind shear.

[ClicheVortex2014]

It won't take much of a bump up to make this a significant event. Just a tick up in moisture return is all we need, we have the lapse rates and wind shear.

Completely agreed. Euro's right on the border of having that more significant threat. It's just weird to have GFS being more aggressive with CAPE than Euro. Looking forward to seeing SPC and Dr. Forbes' thoughts tomorrow, as well as whatever madness 12z NAM musters up since it'll be in range.

[andyhb]

Sheesh I typed "significant" way too many times in that post. Probably should head to bed.

[bl5585]

It's just weird to have GFS being more aggressive with CAPE than Euro.

 

For this run does the time it's coming through have anything to do with it? The GFS has it going through Eastern Illinois at about the warmest time of the day while the Euro pushed it into the evening when things have already started cooling down a bit.

[ClicheVortex2014]

For this run does the time it's coming through have anything to do with it? The GFS has it going through Eastern Illinois at about the warmest time of the day while the Euro pushed it into the evening when things have already started cooling down a bit.

Not really. Euro and GFS differ on not only placement of greatest instability (i.e., location of severe threat), but also magnitude of the instability. Euro places the severe threat further west than GFS, but the severe threat is probably lesser than GFS because the instability is lesser. But even on Euro, it's certainly not something to neglect because, as stated earlier, it's bordering on a more serious threat.

[IllinoisWedges]

Since I saw someone mention the NAM, I just thought I'd pop in and say that it's already putting out high 50/low 60 dews with high 60/low 70 temps in Illinois/Indiana at 18z with the front still sitting out in E Missouri/Iowa. 988 mb sitting in N Iowa. 

[HillsdaleMIWeather]

Very worrying sounding on the 06Z NAM at hour 84 in Central IL

 

[IllinoisWedges]

Day 4 from the SPC

 

 

 

...D4/TUE IN THE MIDWEST...
ON THE LARGE SCALE...A CONSISTENT SIGNAL PERSISTS WITH AN AMPLIFYING
SHORTWAVE TROUGH OVER THE LOWER MO VALLEY TOWARDS THE CENTRAL GREAT
LAKES. THIS SHOULD RESULT IN PRONOUNCED CYCLOGENESIS AS A POWERFUL
MID-LEVEL JET INTENSIFIES FROM THE OZARK PLATEAU TO THE MID-MS
VALLEY. WITH BOUNDARY-LAYER MOISTURE LIKELY TO REMAIN MODEST WITH
PREVAILING LOW-LEVEL WLYS IN PRECEDING DAYS ACROSS THE NRN
GULF...BUOYANCY SHOULD BE WEAK. BUT GIVEN THE STRENGTH OF THE
DEEP-LAYER WIND FIELD AND FORCING FOR ASCENT...POTENTIAL EXISTS FOR
A FAST-MOVING CONVECTIVE LINE ALONG AN ACCELERATING COLD FRONT.
BELOW-AVERAGE CONFIDENCE EXISTS IN THE LOCATION OF THIS FRONT
RELATED TO DIFFERENCES IN TIMING OF CYCLOGENESIS. AS SUCH...AT LEAST
DAMAGING WIND POTENTIAL IS EVIDENT ANYWHERE FROM THE MID-MS VALLEY
TO THE UPPER OH VALLEY. AT THIS TIME...WILL HIGHLIGHT THE MOST
PROBABLE CORRIDOR WITH AN EXPECTATION FOR EXPANSION OF SLIGHT-RISK
PROBABILITIES AS PREDICTABILITY INCREASES.

 

[Indystorm]

Adequate moisture return always seems to be the prime variable in these late winter/early spring events here in the Midwest.  Will have to see if today's model runs amp the threat upward for IL/IN. especially as SPC indicates at present.  I wonder how much the intense rain and flooding in TX/LA/AR will affect moisture return in this situation.

[janetjanet998]

Adequate moisture return always seems to be the prime variable in these late winter/early spring events here in the Midwest.  Will have to see if today's model runs amp the threat upward for IL/IN. especially as SPC indicates at present.  I wonder how much the intense rain and flooding in TX/LA/AR will affect moisture return in this situation.

American models have been overdoing moisture 12z NAM bring low 60 dewpoints all the way to I-80 in IL by 21z with SBCAPES of 2500

 

upper 50's dewpoints  seem more likley

 

however all the rain down south plus the rain falling over IL the next couple of days may help moist the atmosphere some

[RCNYILWX]

American models have been overdoing moisture 12z NAM bring low 60 dewpoints all the way to I-80 in IL by 21z with SBCAPES of 2500

upper 50's dewpoints seem more likley

however all the rain down south plus the rain falling over IL the next couple of days may help moist the atmosphere some

NAM is by far more aggressive with moisture, also owing to quicker northward progression of the surface low and warm front. Will need the better moisture in place to make this threat more interesting. Slower timing on the 00z ECMWF and 06z GFS really limits potential instability.

On the plus side, there's good agreement on steep midlevel lapse rates around mid-day, so decent instability could be attainable if the moisture/higher dews can make it northward.

If the severe threat doesn't materialize, the setup is quite favorable for a strong synoptic wind event as the surface low rapidly deepens Tuesday night.

[Stebo]

NAM is by far more aggressive with moisture, also owing to quicker northward progression of the surface low and warm front. Will need the better moisture in place to make this threat more interesting. Slower timing on the 00z ECMWF and 06z GFS really limits potential instability.

On the plus side, there's good agreement on steep midlevel lapse rates around mid-day, so decent instability could be attainable if the moisture/higher dews can make it northward.

If the severe threat doesn't materialize, the setup is quite favorable for a strong synoptic wind event as the surface low rapidly deepens Tuesday night.

Agree wholeheartedly. The thing with the instability too, 1000 J/kg would be enough to get this going and anything above that could make this a significant event. It won't take much moisture to go from 500 J/kg to 1500 J/kg with these steep lapse rates. Really the only ingredient in question is the moisture, we have the cooling aloft and the strong directional/speed shear that would be in place. If anything close to the NAM verified we'd be looking at one hell of an event.

[Stebo]

I will say this about the NAM, it does have a few things going for it that other models might not pick up on. It is more realistic with the temperature profile than the GFS and with the strong moisture advection it would pull north the higher dew points. Also it is showing good moisture pooling along the boundaries which the GFS doesn't resolve well. Something to keep an eye on as we get closer to Tuesday.

[Hoosier]

Not much to add here, but one thing I will say is that I like the lack of convection to the south for this setup.  Always nice when you don't have to wonder about whether it may have a detrimental effect.

[Stebo]

Not much to add here, but one thing I will say is that I like the lack of convection to the south for this setup.  Always nice when you don't have to wonder about whether it may have a detrimental effect.

Yeah the road will be open, the question is how long will we have the open road before the event itself.

[RCNYILWX]

The 12z run of the Euro is much less enthused with low level moisture with slower timing of the warm front lifting north. Very backed east-southeast winds pulling on drier air to the east keeping dews in the 40s most of the LOT CWA by 18z and still into far northeast IL and northwest IN by 00z. Best moisture/mid 50s dews get up to central IL by 00z. Still may be enough CAPE generated with that sort of profile for a strongly forced line and wind threat as SPC alluded to, especially given the impressive wind fields.

This one is definitely worth monitoring because of everything mentioned so far and better potential if we can get the moisture to surge in quicker but would like to see globals get on board (particularly the Euro which has more realistic thermos typically than GFS) in next few days before getting more concerned.

[HillsdaleMIWeather]

IWX calling this a "bona fide" severe threat

REGARDLESS PRIMARY MET FOCUS CNTRS ON NXT UPSTREAM POTENT NEPAC SYS

AS IT ABRUPTLY AMPLIFIES STGLY EWD OVR THE WRN LAKES LT DY4(TUE).

THIS PD CONTS TO LOOK QUITE INTERESTING WRT CONV POTENTIAL. WHILE

NWD INFLUX/TRANSPORT OF RICHER BNDRY LYR MSTR UNCERTAIN...

JUXTAPOSITIONING OF MULTI-MODEL SFC TRIPLE POINT AND UPSTREAM MID

LVL SPEED MAX ALIGNED ACRS CNTRL/ERN IL TUE AFTN CERTAINLY

SUGGESTS A BONA-FIDE SVR RISK PRESENT. NOT ONLY ALG SHARP NWD RTNG

WMFNT BUT WITHIN NWD NARROWING WARM SECTOR AHD OF SHARP

CDFNT...W/BOTH SFC FTRS CAPABLE OF INITIATING CONVN BY LT AFTN INADV

OF RAPIDLY DEEPENING CYCLONE. WILL DUMP TUE AM POPS AS ANY INFLUENCE

FM THIS SYS REMAINS WEST AND RTN LL MSTR/THETA-E BULGE STILL WELL

S/SW OF CWA ALTHOUGH THAT CHGS SIGLY BY MID-LT AFTN

[tornadohunter]

Well 18z nam increased cape

[Hoosier]

Yes, NAM still pretty bullish with moisture return. We'll see what future runs have.

[JasonOH]

I know this isn't the OV, but the NAM nailed the dew point in western OK last Monday. The cap still held but it did a good job with the dews, especially considering how bullish it was. I don't see a reason to discount it's moisture at this time.

[HillsdaleMIWeather]

18Z GFS increased Cape as well.