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July 12-15, 2014 Severe Weather Threat


Chicago WX

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I'm concerned about the 4km NAM showing what may be quasi-discrete convection in the metro later.  This seems like a situation where there might be an unwelcomed lake-driven baroclinicity-induced surprise in the metro or NWI this evening.

 

Yeah that model definitely looks a bit concerning..

2jag1s4.jpg

 

Updraft helicity..

m9q45k.jpg

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I'm concerned about the 4km NAM showing what may be quasi-discrete convection in the metro later. This seems like a situation where there might be an unwelcomed lake-driven baroclinicity-induced surprise in the metro or NWI this evening.

Yeah just looked. That sure is interesting. Add the training and heavy rainfall threat late tonight on that run as well.

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Areas just northwest of Champaign and into Champaign have received 4 to 7" of rain per reports. Champaign alone has received 4.60" in the last 4 hours, just goes to show you how juicy the atmosphere is today. If Chicago were to get trained this evening into tonight it could get very bad very quickly.

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The 14z HRRR is pretty scary for eastern IA with that all by itself supercell. You can see it enhancing it's near storm environment in the sfc wind field and sig tor max out to it's immediate SE in model land.

 

Yeah it shows that beast riding along an area of some higher mid-level support as well.  Showing a nice pocket of 55kts at H5.

 

3027xas.jpg

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patches of blue sky overhead.....72/71 currently

 

low level clouds hauling butt out of the SW .... mid level clouds sliding at much lower pace due east...

 

a casual non-met obs that i'm sure is obvious to most but.....the racing low level clouds always seems to be indicative of a decent event in the making down the road in time

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New day 2

 

 

 

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1229 PM CDT SAT JUL 12 2014  
 
VALID 131200Z - 141200Z  

 
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MS/OH VALLEYS TO  
WRN PA/NY...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS WILL BE POSSIBLE OVER PARTS OF THE OHIO AND  
MID-MISSISSIPPI VALLEYS ON SUNDAY. MORE ISOLATED STRONG TO SEVERE  
STORMS WILL ALSO BE POSSIBLE ACROSS PART OF THE NORTHEAST AND  
MID-ATLANTIC STATES...THE FRONT RANGE AND CENTRAL PLAINS...THE  
SOUTHWEST...AS WELL AS OREGON.  
   
..SYNOPSIS
 
 
A LARGE POSITIVELY-TITLED MID-UPPER LEVEL TROUGH WILL CONTINUE TO  
AMPLIFY ON SUNDAY ACROSS THE UPPER MS VALLEY/GREAT LAKES REGION. A  
STRENGTHENING CYCLONIC FLOW REGIME IS FORECAST TO DEVELOP SWD INTO  
THE CENTRAL PLAINS...OH VALLEY AND NORTHEAST STATES. MIDLEVEL  
IMPULSES...CURRENTLY MOVING ACROSS SRN WY AND THE NEB PANHANDLE  
REGIONS PER WATER VAPOR IMAGERY...ARE EXPECTED TO MOVE ACROSS THE  
MID MS/OH VALLEYS AND NORTHEAST STATES THIS FORECAST PERIOD.  
MEANWHILE...HIGH PRESSURE WILL REMAIN ANCHORED OVER THE GREAT BASIN.  
A COMPACT SHORTWAVE TROUGH...CURRENTLY LOCATED WEST OF CA NEAR  
35.5N/133.7W REMAINS FORECAST TO MOVE INTO ORE/WA AFTER 14/00Z.  
 
AT THE SURFACE...A COLD FRONT WILL ADVANCE SWD THROUGH THE OH AND  
MID MS VALLEYS...WITH THE TRAILING PORTION MOVING INTO OK AND THE  
SRN HIGH PLAINS. THE NERN EXTENT OF THIS COLD FRONT IS EXPECTED TO  
ADVANCE ACROSS NY AND NRN NEW ENGLAND MAINLY SUNDAY NIGHT.  
   
..OH/MID MS VALLEYS
 
 
A VERY MOIST ENVIRONMENT /PW OF 1.75-2+ INCHES/ IS EXPECTED ACROSS  
THE WARM SECTOR IN ADVANCE OF THE SWD MOVING COLD FRONT. DESPITE  
WEAK MIDLEVEL LAPSE RATES...DIABATIC HEATING AND THE RICH MOISTURE  
WILL RESULT IN MLCAPE OF 1500-2500 J/KG. GRADUALLY-STRENGTHENING  
WSWLY MID-UPPER LEVEL WINDS WILL RESULT IN THE STRONGEST EFFECTIVE  
BULK SHEAR EXTENDING FROM THE MID MS VALLEY THROUGH THE OH VALLEY.  
GIVEN THESE SHEAR VECTORS WILL BE PARALLEL TO THE COLD FRONT AND  
DIFFERENTIAL HEATING BOUNDARIES...BOWING LINE SEGMENTS WILL BE  
LIKELY...WHILE EFFECTIVE BULK SHEAR UP TO 35-40 KT WILL ALSO SUPPORT  
SUPERCELL DEVELOPMENT. ALL SEVERE HAZARDS WILL BE POSSIBLE.

 

post-4544-0-41095400-1405187086_thumb.gi

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DVN:

 

 

 

.UPDATE...
ISSUED AT 1249 PM CDT SAT JUL 12 2014

WARM AND VERY HUMID CONDITIONS IN PLACE AT MIDDAY WILL LEAD TO
CONTINUED DESTABILIZATION THIS AFTERNOON...ESPECIALLY OVER THE
SOUTH...AS CLEARING SEEN ON SATELLITE OVER S CENTRAL IA
PROGRESSES EASTWARD. MORE DENSE CLOUD COVER STREAMING ACROSS THE
NORTHERN HALF OF THE FORECAST AREA SHOULD CAP HIGHS CLOSER TO
80...WHILE THE SOUTH SHOULD STILL REACH THE UPPER 80S AND CLOSE TO
90. SEVERAL MOSTLY WEST TO EAST ORIENTED LOW LEVEL MESOSCALE
BOUNDARIES IN PLACE OVER THE AREA WILL BE WATCHED AS CONVECTION IS
LIKELY TO BREAK OUT WHEN CONVECTIVE TEMPERATURES ARE REACHED AND A
MID LEVEL SHORTWAVE ADVANCING FROM THE MO RIVER VALLEY ACTS AS A
TRIGGER. ASSOCIATED ENHANCED DEEP SHEAR...AND POSSIBLE LOW LEVEL
BACKING SURFACE WINDS MAY LEAD TO SOME SUPERCELL STORMS WITH
DAMAGING WIND AND ISOLATED TORNADOES THE PRIMARY THREATS. AT THIS
TIME...THIS IS LIKELY TO BREAK OUT OVER THE NW AFTER 3 PM AND
SPREAD OVER THE FORECAST AREA LATE AFTERNOON INTO THIS EVENING.
WILL BE WATCHING CLOSELY THE PARAMETERS FROM OUR 18Z SPECIAL UPPER
AIR SOUNDING THAT IS CURRENTLY UNDERWAY.
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Yeah low level clouds are zipping by. Dark skies to the west with some clear spots here currently. The air has that feeling like something's gonna happen. Had the windows recaulked this morning. Should be put to the test tonight.

patches of blue sky overhead.....72/71 currently

low level clouds hauling butt out of the SW .... mid level clouds sliding at much lower pace due east...

a casual non-met obs that i'm sure is obvious to most but.....the racing low level clouds always seems to be indicative of a decent event in the making down the road in time

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Yeah low level clouds are zipping by. Dark skies to the west with some clear spots here currently. The air has that feeling like something's gonna happen. Had the windows recaulked this morning. Should be put to the test tonight.

 

 

good luck with the caulk job! 

 

weaker ribbon of convergence running from Galesburg to Des Moines @ 18Z

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MCD for southern half or so of Iowa....

 

 

   MESOSCALE DISCUSSION 1345
   NWS STORM PREDICTION CENTER NORMAN OK
   0348 PM CDT SAT JUL 12 2014

   AREAS AFFECTED...SERN NEB / SRN HALF OF IA / FAR NWRN MO

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

   VALID 122048Z - 122245Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...CONVECTIVE INITIATION TIMING REMAINS UNCLEAR BUT THE
   POTENTIAL ISOLD SEVERE THREAT WILL LIKELY INCREASE LATER THIS
   AFTERNOON AND INTO THE EVENING HOURS.

   DISCUSSION...VISIBLE IMAGERY AND SURFACE OBSERVATION TRENDS OVER THE
   PAST FEW HOURS HAVE SHOWN THE DEVELOPMENT OF A CU FIELD ALONG AND
   BEHIND A COLD FRONT/WIND SHIFT OVER CNTRL IA WWD INTO FAR ERN NEB.
   CLOUD DEBRIS AND CONVECTIVE OUTFLOW HAVE RESULTED IN A DIFFERENTIAL
   HEATING BOUNDARY DRAPED FROM CNTRL IL ARCING WNWWD INTO W-CNTRL IA
   INTERSECTING THE FRONT.  THE AIRMASS S OF THE AFOREMENTIONED
   BOUNDARIES CONTINUES TO HEAT AND DESTABILIZE WITH TEMPS RISING
   THROUGH THE UPPER 80S AND INTO THE LOWER 90S AMIDST DEWPOINTS IN THE
   LOWER TO MID 70S. 

   19Z RAP SOUNDINGS AND THE 18Z DVN RAOB MODIFIED FOR CURRENT SURFACE
   CONDITIONS OVER SRN IA...RESULT IN LITTLE IF ANY APPRECIABLE
   REMAINING CINH AND UPWARDS OF 1500-3000 J PER KG MLCAPE.  THE KDMX
   VWP SHOWS AROUND 40 KT AT H5 FLOW AND WOULD SUPPORT POTENTIAL STORM
   ORGANIZATION...INCLUDING SUPERCELLS --ONCE STORMS FORM.  DESPITE A
   WEAK SHORTWAVE TROUGH SHEARING NEWD ACROSS WI INTO THE UPPER GREAT
   LAKES THIS AFTERNOON...IT APPEARS ADDITIONAL FORCING FOR ASCENT
   INFLUENCING THE REGION NAMELY IN THE FORM OF UPPER ASCENT ASSOCIATED
   WITH A POWERFUL UPPER TROUGH OVER THE UPPER MIDWEST REGION AND THE
   CONCURRENT STRENGTHENING OF THE LOW LEVEL JET THIS EVENING TOWARDS
   THE MID MS RIVER VALLEY AND NRN IL WILL BE NEEDED TO PROMOTE STORM
   DEVELOPMENT.  ONCE THIS OCCURS...A SEVERE THREAT MAINLY IN THE FORM
   OF ISOLD LARGE HAIL...DMGG WINDS...AND PERHAPS A TORNADO OR TWO WILL
   LIKELY PROMPT A WATCH ISSUANCE.

   ..SMITH/HART.. 07/12/2014

 

90/77 @ SDA in SW Iowa.... shticky

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Surprised this hasn't been mentioned yet on this thread but the heavy rains earlier today wiped out the Taste of Chicago in its entirety for today (it's still on for tomorrow).  Tribune story:

 

http://www.chicagotribune.com/news/local/breaking/chi-chicago-weather-forecast-20140712,0,4965822.story?track=rss

 

Also the John Deere Classic PGA tournament in the QCs (Silvis) is also within the area noted in the SPC's latest MD (plus the CBS announcers said earlier that the overnight rains and the threat of more storms today resulted in split-course play (IIRC--I am not a golf expert, I just have it on TV now).

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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 411

NWS STORM PREDICTION CENTER NORMAN OK

500 PM CDT SAT JUL 12 2014

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF

SOUTHERN AND EASTERN IOWA

NORTHWEST ILLINOIS

NORTHERN MISSOURI

* EFFECTIVE THIS SATURDAY AFTERNOON FROM 500 PM UNTIL MIDNIGHT

CDT.

* PRIMARY THREATS INCLUDE...

A COUPLE TORNADOES POSSIBLE

SCATTERED DAMAGING WIND GUSTS TO 70 MPH LIKELY

ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 100 STATUTE

MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHEAST OF CEDAR

RAPIDS IOWA TO 30 MILES SOUTH SOUTHEAST OF LAMONI IOWA. FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS.

&&

DISCUSSION...SCTD TSTMS EXPECTED TO FORM THROUGH MID-EVE IN

MOIST...VERY WARM...AND CONFLUENT WSWLY LOW-LVL FLOW AHEAD OF

ACCELERATING COLD FRONT NOW EXTENDING FROM NE IA TO SE NEB.

LARGE-SCALE ASCENT MAY BE ENHANCED BY WEAK IMPULSE TRACKING ENE

ACROSS NEB/IA AHEAD OF AMPLIFYING NRN STREAM TROUGH NOW OVER SRN MB.

COMBINATION OF STRENGTHENING LLJ...MOIST LOW-LVL

ENVIRONMENT...COOLING BOUNDARY LAYER...AND SEMI-DISCRETE STORMS

SUGGESTS POTENTIAL FOR A COUPLE TORNADOES IN ADDITION TO SVR

WIND/HAIL.

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