Jump to content
  • Member Statistics

    17,502
    Total Members
    7,904
    Most Online
    Weathernoob335
    Newest Member
    Weathernoob335
    Joined

June 28-July 8th Severe Potential


Chicago Storm

Recommended Posts

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1257 AM CDT WED JUN 27 2012

VALID 281200Z - 291200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF IA

NRN IL AND

FAR NW IND...

..CNTRL PLAINS/UPPER MS VALLEY/SRN GREAT LAKES

AN UPPER-LEVEL RIDGE IS FORECAST TO MOVE EWD ACROSS THE GREAT LAKES

REGION ON THURSDAY AS HIGH PRESSURE REMAINS DOMINANT ACROSS THE

SCNTRL US. A SUBTLE UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS

THE UPPER MS VALLEY. AT THE SFC...A SLOW MOVING BUT ILL-DEFINED COLD

FRONT SHOULD BE IN PLACE FROM NRN NEB EXTENDING EWD ACROSS IA...SRN

WI AND INTO LOWER MI. ALONG AND SOUTH OF THE BOUNDARY...SFC

DEWPOINTS IN THE UPPER 60S AND LOWER 70S F SHOULD RESULT IN STRONG

DESTABILIZATION BY AFTERNOON. THUNDERSTORM DEVELOPMENT COULD OCCUR

ANYWHERE ALONG THE BOUNDARY BUT THE CONVECTION IN MANY AREAS COULD

STRUGGLE DUE TO THE WARM AIR ALOFT.

FORECAST SOUNDINGS AT 00Z/FRI ALONG THE BOUNDARY FROM CNTRL IA EWD

TO NRN IL SHOW IMPRESSIVE THERMODYNAMICS WITH MLCAPE FROM 4000 TO

5000 J/KG. IN ADDITION...0-6 KM SHEAR IN THE DES MOINES AND CHICAGO

AREAS ARE FORECAST TO BE IN THE 40 TO 50 KT RANGE. THIS SHOULD

SUPPORT SUPERCELL DEVELOPMENT ALTHOUGH LARGE-SCALE ASCENT SHOULD

REMAIN WEAK KEEPING STORM COVERAGE ISOLATED. ANY STORMS THAT CAN

DEVELOP IN THE EXTREMELY UNSTABLE AIRMASS SHOULD HAVE A POTENTIAL

FOR DAMAGING WIND GUSTS. ISOLATED LARGE HAIL WILL ALSO BE POSSIBLE.

FURTHER TO THE WEST ACROSS THE CNTRL PLAINS...ISOLATED THUNDERSTORMS

SHOULD ALSO DEVELOP ALONG THE BOUNDARY FROM FAR NE CO INTO CNTRL

NEB. FORECAST SOUNDINGS ALONG THIS CORRIDOR SHOW MLCAPE VALUES FROM

3000 TO 4000 J/KG WITH 0-6 KM SHEAR AROUND 30 KT. THIS SHOULD

SUPPORT A MARGINAL SEVERE THREAT WITH MULTICELLS THAT CAN DEVELOP IN

SPITE OF THE WARM AIR ALOFT.

Link to comment
Share on other sites

  • Replies 845
  • Created
  • Last Reply

You know...if we hold on to, say 65-70 dewpoints right near the boundary Thursday evening, there'd easily be 4000J/kg of CAPE. Add in some pretty strong bulk shear, and you've got a recipe for a really intense HP supercell or two. The trick, as well-noted in the SWODY2, would be getting the storms to form in the first place.

Link to comment
Share on other sites

I'm flipping back and forth on this...I fully bought into the ample instability days ago, not the crazy GFS numbers but plenty and the noted shear is a bonus...so yeah the pump will be primed. The forcing is just giving me a hard time and at this time i'm leaning towards the cap holding...at least thursday.

Link to comment
Share on other sites

the current SPC day 2 discussion still talks about large scale ascent being on the weak side..it will be interesting to see which way they lean on the updated version this afternoon

I do have to admit if these shortwaves that the NAM/GFS are showing verify that would be probably enough ascent to bust the cap, especially if we can realize the dews I had mentioned Monday (67-71) range, considering both here and there might be in the vicinity of 100-108.

temp33.gif

Link to comment
Share on other sites

New day 2 outlook

DOMINANT UPPER HIGH WILL REMAIN IN PLACE ACROSS THE CONUS INTO THE DAY2 PERIOD WITH FLATTENING EXPECTED NEAR THE U.S. CANADIAN BORDER AS MB/ON SHORT-WAVE TROUGH TOPS THE RIDGE AND BEGINS TO DIGS SEWD LATE IN THE PERIOD. VERY WARM EML HAS OVERSPREAD MUCH OF THE COUNTRY AND A STRONG CAP WILL LIKELY PROVE HOSTILE TOWARDS DEEP CONVECTION...ESPECIALLY ORGANIZED ROBUST DEEP CONVECTION. ONE EXCEPTION WILL BE ALONG THE NERN EDGE OF THE STEEP LAPSE RATE PLUME WHICH HAS BEEN DISPLACED UNUSUALLY FAR DOWNSTREAM ACROSS THE GREAT LAKES/OH VALLEY. GIVEN THE VERY WARM MID LEVEL TEMPERATURES IT APPEARS SFC-BASED THUNDERSTORMS WILL STRUGGLE TO DEVELOP AS CONVECTIVE TEMPERATURES WILL LIKELY NOT BE REACHED AHEAD OF THE COLD FRONT. FOR SFC PARCELS TO FREELY CONVECT READINGS WILL NEED TO RISE WELL ABOVE 100F. ADDITIONALLY...LATEST MODEL GUIDANCE IS LIKELY TOO AGGRESSIVE REGARDING FORECAST SFC DEW POINTS IN THE MID 70S AHEAD OF THE WIND SHIFT. EVEN SO...THERE IS SOME CONCERN THAT FRONTAL ASCENT/WEAK WARM ADVECTION ALOFT WILL ENCOURAGE POST-FRONTAL ELEVATED CONVECTION THAT COULD ATTAIN ROBUST LEVELS GIVEN THE STEEP LAPSE RATES. THE MOST LIKELY AREA FOR THIS WILL BE ACROSS THE LOWER GREAT LAKES AFTER DARK WITH SUBSEQUENT SEWD MOVEMENT/DEVELOPMENT ALONG THE ERN EDGE OF STRONG EML THROUGH THE UPPER OH VALLEY INTO PORTIONS OF CNTRL PA BY MORNING. FOR THIS REASON HAVE EXPANDED 5% SEVERE PROBS TO ACCOUNT FOR STRONG ELEVATED TSTMS DURING THE LATTER HALF OF THE PERIOD.

Link to comment
Share on other sites

IWX Wed. afternoon AFD emphasizes that models are grossly overestimating dews this far east given dryness of soil and that will inhibit t storm formation in a pattern that would normally be favorable. They also mention that any MCS diving in from the NW would tend to dry up before reaching the Michiana area and give only a 10% chance of precip in the short term period.

Link to comment
Share on other sites

ILN AFD mentions the potential of a high end damaging wind MCS event if everything comes together just right.

BETTER SIGNAL FRIDAY/FRIDAY NIGHT...THAT IF WEAK SYSTEMS IN

INCREASINGLY NWLY MID LEVEL FLOW CAN ERODE CAPPING...A HIGH END

DAMAGING WIND MCS EVENT IS POSSIBLE...AS THE SYNOPTIC SETUP WILL

BE AN IDEAL DERECHO TYPE ENVIRONMENT WITH EXTREME INSTABILITY ON

THE EDGE OF THE CAP AND STRONG NWLY MID LEVEL FLOW. KEY WILL BE

FORCING AND WHETHER IT WILL BE STRONG ENOUGH TO DO SO...AND STRONG

ENOUGH TO MAINTAIN THROUGH VERY WARM EML. LOW CHANCE OF IT

OCCURRING...BUT IF SOMETHING GOES...IT COULD BE SIGNIFICANT

CONSIDERING MLCAPE/SHEAR PARAMETER SPACING ON FORECAST SOUNDINGS.

Link to comment
Share on other sites

On friday night. I think tomorrow is going to stay capped.

Hmm nope, it has it tomorrow night.

I personally don't think we'll know for sure until we get a good look at WV tomorrow to try and diagnose the strength of the embedded disturbances riding around the ridge tomorrow. It's easy to just blurt out that it's gonna be capped with H7 temps at 15C. But the NAM shows subtle CAA at H7 in the evening, and with such intense low-level heating, the cap won't quite as substantial as you think. Add in that H85 WAA will be ongoing (another forcing for acsent), a decent shortwave could do the trick.

Link to comment
Share on other sites

yep lights up the frontal boundary after 0z and they track east along/north of it.

you're right, my fault. i hadn't had a chance to look at the 00z runs yet. I think both tomorrow night (thurs) and friday night have a good chance at a fairly substantial mcs threat. we shall see. like you said, would like to see the wv in the morning first.

ps, my girlfriend goes to UAH tornadotony! :tomato:

Link to comment
Share on other sites

you're right, my fault. i hadn't had a chance to look at the 00z runs yet. I think both tomorrow night (thurs) and friday night have a good chance at a fairly substantial mcs threat. we shall see. like you said, would like to see the wv in the morning first.

ps, my girlfriend goes to UAH tornadotony! :tomato:

Very cool! Yeah there is some pretty good potential for the next few days.

Link to comment
Share on other sites

In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA.

Link to comment
Share on other sites

In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA.

The question is, who wins out lol... we shall see. :)

Could you post the links to those sim radars? just curious if i found the same ones.

Link to comment
Share on other sites

In an odd twist from the norm, the WRF-ARW and NSSL WRF models are the most bullish of the high-res model suite, with the WRF-NMM and EMC WRF showing very little, the NSSL WRF showing a likely supercell to MCS transition, with initiation at the lake-breeze/frontal interface around 2200 UTC and moving SE through Chicago and NW IN, and the ARW showing a very intense MCS along the front tomorrow night initiating in IA.

Kinda looks like the NAM then turning it ESE as it makes it's way across IL during the early morning hours Friday.

Link to comment
Share on other sites

6z NMM comes around and blows up a monster cell over lake michigan.

I'm still leaning against anything beyond hyper isolated convection in the LOT area and have a hard time arguing with local offices and the SPC. I'd probably favor a disorganized complex riding just north of the IL/WI border...maybe we'll get lucky and see the tail build south into the lake breeze convergence but that's an outside shot IMO.

some isolated elevated showers have gone up along the waa in eastern iowa...

ASOS/AWOS SITES

ACROSS EASTERN IA REPORTING CLOUD BASES GENERALLY IN THE

9000-15000 FT RANGE...AND CEDAR RAPIDS RECENTLY REPORTED TSRA WITH

CLOUD BASES AT 11000 FT!

arizona style ftl

Link to comment
Share on other sites

NWS in Northern Indiana saying no severe weather at all overnight tonight...

IN TERMS OF PRECIP POTENTIAL /AND POSSIBLE IMPACTS ON TEMPS

TODAY/...THE HI RES MODELS CONTINUE TO BRING SEVERAL WEAK WAVES

THROUGH THE FLOW SPARKING OFF MCS DEVELOPMENT TO THE WEST OF THE

AREA AND MOVING ACROSS S LWR MI INTO N INDIANA. HOWEVER...WHERE

THESE SAME MODELS ARE SHOWING CONVECTION SHOULD BE

OCCURRING...CONDITIONS ARE PRESENTLY DRY. UNSTABLE CONDITIONS WILL

BE IN PLACE...BUT 700 MB TEMPS IN THE +13 TO +16 CELSIUS RANGE DOES

NOT BODE WELL FOR CONVECTIVE DEVELOPMENT IN THE ABSENCE OF STRONG

FORCING OR UPPER LEVEL COOLING. THESE FACTORS COMBINED WITH PAST

HISTORY OF RECENT MCS DEVELOPMENT EITHER FALLING APART AS THEY ENTER

OR BYPASSING THE AREA TO THE NORTH...WARRANT GOING AGAINST SOME OF

THE SURROUNDING OFFICES AND KEEPING A DRY FORECAST. THE SAME

GUIDANCE THAT BRINGS IN MID 70 OR HIGHER DEWPTS BARELY HAS 30 POPS

IN.

That is from their AFD early this morning at 424am edt.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...