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July 11-14 Severe Weather Event

Powerball

By Powerball,
in Lakes/Ohio Valley

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ClicheVortex2014

ClicheVortex2014

Posted
Posted

ILX

 

.LONG TERM...(MONDAY THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN JUL 12 2015

PRIMARY CONCERN THRU EARLY TUESDAY MORNING WILL BE WITH THE THREAT
FOR WIDESPREAD SEVERE WEATHER AS SEVERAL ROUNDS OF THUNDERSTORMS ARE
EXPECTED TO TRACK SOUTHEAST INTO PARTS OF CENTRAL THROUGH EAST
CENTRAL AND SOUTHEAST ILLINOIS. IN ADDITION...HEAT INDEX VALUES
ARE EXPECTED TO BE WITHIN A DEGREE OR TWO OF 105 TOMORROW AFTERNOON
ESPECIALLY ACROSS THE WEST...AS A RESULT...WILL ISSUE A HEAT
ADVISORY FOR AREAS ROUGHLY ALONG AND WEST OF A TAYLORVILLE TO
LINCOLN TO HENRY LINE. IF THUNDERSTORM COVERAGE IS NOT AS
ANTICIPATED TOMORROW MORNING...WE MAY HAVE TO EXPAND THE ADVISORY
FURTHER EAST. ADDITIONAL HEAVY RAINFALL IS ALSO A CONCERN WITH THE
SEVERAL ROUNDS OF STORMS EXPECTED...HOWEVER...LATEST MODEL DATA
HAS SHIFTED THE AXIS A BIT FURTHER TO THE EAST. THIS WOULD FAVOR
THE HEAVIER RAINS EAST OF I-55 WHERE FLASH FLOOD GUID VALUES WERE
QUITE LOW...THANKS TO THE RAINFALL OVER PARTS OF THE AREA OVER THE
PAST 24 HOURS.

CONVECTIVE INDICES STILL VERY IMPRESSIVE TOMORROW AFTERNOON AND
EVENING AHEAD OF A RATHER STRONG SHORTWAVE FOR JULY THAT IS
FORECAST TO TRACK ACROSS THE LOWER GREAT LAKES. MIXED LAYER CAPES
OF AROUND 5000 J/KG WITH 0-6KM SHEAR VALUES OF 50-60 KTS FORECAST
BY THE NAM TOMORROW AFTERNOON AND EVENING WITH VERY LITTLE IF ANY
CONVECTIVE INHIBITION. 700-500 MB LAPSE RATES OF 7.5-8.5 DEG/C
SEEN OVER A WIDE AREA OF THE CORN BELT TOMORROW AFTERNOON AND
EVENING AS WELL. WHATEVER CONVECTION WE SEE IN THE MORNING SHOULD
PUSH AWAY FROM OUR AREA BY LATE MORNING/EARLY AFTERNOON WITH
SEVERAL HOURS FOR THE ATMOSPHERE TO RECOVER BEFORE THE NEXT STORM
COMPLEX DEVELOPS TO OUR NORTH AND TRACKS SSE ACROSS CENTRAL
ILLINOIS LATE IN THE AFTERNOON OR MORE LIKELY DURING THE EVENING
WITH DAMAGING WINDS AND LARGE HAIL ASSOCIATED WITH THE FAST MOVING
LINE OF STORMS WITH ISOLATED QLCS TORNADOES QUITE POSSIBLE WITH
THE EXTREME INSTABILITY AND STRONG DEEP LAYERED SHEAR. THE STORM
THREAT WILL DIMINISH LATE IN THE EVENING WITH A FEW MODELS STILL
TRYING TO BRING ANOTHER MCS SOUTH INTO AT LEAST EASTERN IL WELL
AFTER MIDNIGHT. SEEMS HARD TO FATHOM THAT AFTER A STRONG-SEVERE
QLCS MOVES THRU IN THE EVENING THAT THE ATMOSPHERE WILL HAVE
SUFFICIENT TIME TO RECOVER. WITH RATHER IMPRESSIVE FORCING
ASSOCIATED WITH THE VIGOROUS UPPER WAVE AND SUCH UNSEASONABLY
STRONG DEEP LAYERED SHEAR...WE WON`T COMPLETELY DISCOUNT THAT IDEA
SO WE WILL HOLD ON TO CHANCE POPS WELL AFTER MIDNIGHT.

 

IWX

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 354 PM EDT SUN JUL 12 2015

MOISTURE STUCK UNDER THE INVERSION HAS KEPT SKIES MOSTLY CLOUDY
AND KEPT TEMPERATURES COOL THUS FAR TODAY. WHILE THE MOISTURE WILL
REMAIN STUCK UNDER THE STRENGTHENING INVERSION...EXPECT ENOUGH
MIXING FOR SOME SUN TO PEEK THROUGH BY LATER TODAY AND WARM
TEMPERATURES INTO THE UPPER 70S TO LOW 80S. THEREFORE DID NOT MAKE
ANY CHANGES TO ONGOING HIGH TEMPERATURE FORECAST FOR TODAY.

CONTINUING TO MONITOR SEVERE WEATHER THREAT FOR MAINLY THE WESTERN HALF
OF THE FORECAST AREA ON MONDAY. WILL NEED TO MONITOR OVERNIGHT
CONVECTIVE TRENDS CLOSELY AS THE TRACK OF THESE STORMS WILL DECIDE
WHERE THE FRONT/COMPOSITE OUTFLOW SETTLES DURING THE DAY ON MONDAY.
WHEREVER THIS BOUNDARY DOES SETTLE...SIGNIFICANT SEVERE WEATHER CAN BE
EXPECTED ALONG AND IMMEDIATELY WEST WITH ALL SEVERE WEATHER TYPES
ANTICIPATED. CURRENT THINKING IS THAT THE REMNANTS OF THE CONVECTION
IN MINNESOTA TONIGHT WILL TRACK THROUGH THE AREA AFTER 12Z. IN THE
WAKE OF THIS CONVECTION...RAPID DESTABILIZATION WILL OCCUR ACROSS
NORTHERN ILLINOIS AND NORTHWEST INDIANA. EFFICIENT
EVAPOTRANSPIRATION FROM THE WELL DEVELOPED AGRICULTURAL CROPS IN
ADDITION TO THE MOIST SOILS FROM THE RECENT WET PATTERN WILL CAUSE
DEWPOINTS TO RISE INTO THE UPPER 70S TO LOW 80S DURING THE AFTERNOON
MONDAY. THIS MOIST BOUNDARY LAYER BENEATH STEEP MID LEVEL LAPSE
RATES IN EXCESS OF 7 C/KM WILL LEAD TO EXTREME MLCAPE NEAR 5000
J/KG. IN ADDITION... ANY STORMS THAT CAN FORM IN THIS ENVIRONMENT
WILL QUICKLY ORGANIZE WITH AROUND 50 KNOTS OF DEEP LAYER SHEAR.

PRIMARY CONCERN FOR SEVERE WEATHER IN OUR FORECAST AREA WILL BE
DURING THE EVENING HOURS. SUPERCELLS WILL FORM ALONG AND AHEAD OF A
SOUTHWARD MOVING COLD FRONT DROPPING OUT OF WISCONSIN. EXPECT THESE
STORMS TO CONGEAL INTO A FORWARD PROPAGATING MCS WHICH WILL TRAVEL
SOUTH SOUTHEASTWARD INTO THE EARLY OVERNIGHT HOURS. WITH DCAPE OVER
1000 J/KG AND A 30 KT 0-3 KM SHEAR VECTOR ORIENTED NEARLY
PARALLEL TO THE STORM MOTION VECTOR...EXPECT WIDESPREAD DAMAGING
WINDS FROM THIS MCS WITH WIND GUSTS OVER 80 MPH POSSIBLE. AGREE
WITH THE CURRENT MODERATE RISK OUTLINE FROM SPC FOR THE GREATEST
THREAT IN OUR FORECAST AREA AT THIS TIME.

IN ADDITION TO THE SEVERE WEATHER THREAT...HAVE ADDITIONAL CONCERNS
ABOUT FLASH FLOODING POTENTIAL CONSIDERING THE POTENTIAL FOR 2
ROUNDS OF CONVECTION ACROSS AN AREA THAT HAS SEEN 400% OF NORMAL
PRECIPITATION IN THE PAST 30 DAYS. WILL HOIST A FLASH FLOOD WATCH
FOR THE SOUTHWESTERN HALF OF THE FORECAST AREA WHERE 2 ROUNDS OF
STORMS ARE MOST LIKELY.

 

IND

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
ISSUED AT 355 PM EDT SUN JUL 12 2015

AFTER INITIAL STORMS CLEAR THE AREA MONDAY MORNING...EXPECT A LULL
BEFORE FOCUS SHIFTS TO WIDESPREAD STORM DEVELOPMENT WHICH APPEARS
LIKELY TO OUR NORTH AND NORTHWEST LATE MONDAY AFTERNOON INTO THE
EVENING. POTENTIAL EXISTS FOR EXTREME INSTABILITY VALUES
WHICH...WHEN COUPLED WITH MORE THAN ADEQUATE DEEP LAYER SHEAR
SUGGEST STORMS WILL RAPIDLY GO SEVERE. INITIAL DEVELOPMENT TO THE
NORTH AND NORTHWEST MAY BE DISCRETE BUT WILL LIKELY QUICKLY
ORGANIZE INTO A SEVERE MCS AND PERHAPS A DERECHO...WITH THE
POTENTIAL FOR WIDESPREAD WIND DAMAGE...LARGE HAIL...AND A FEW
TORNADOES. MODERATE RISK IS WELL JUSTIFIED. ADDITIONALLY...A
CONTINED VERY MOIST AIRMASS WILL MAKE HEAVY RAIN AND FLASH
FLOODING A CONTINUED THREAT...THUS THE FLASH FLOOD WATCH WILL
CONTINUE THROUGH 09Z TUESDAY.

 

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Hoosier

Hoosier

Posted
Posted

Can only imagine how humid that type of DP would feel like. It'll make the low/mid 70F dews here seem pleasant. 

 

 

I experienced 80+ in LAF multiple times.  Instant perspiration once you step outside.  Although honestly, it doesn't feel a whole lot different than dewpoints in the 70s

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Quincy

Quincy

Posted
Posted

Six sites in Iowa, and two in Minnesota have dews AOA 80 currently. Many others in the 78-79 range as well. Since the models have a handle on today, it's looking like widespread 80-82 dews tomorrow as long as the morning convection doesn't mess things up too much.

I have some doubts about convective coverage into IA/IL tonight. Strong confidence in plenty of action up in MN, but trends lead me to lean toward less coverage with southward extent than some model guidance. I wouldn't rule out convective activity into N IL, but likely not enough to have much (if any) of a negative impact on tomorrow's setup.
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ClicheVortex2014

ClicheVortex2014

Posted
Posted

Gonna go work out, shave, shower, and get ready for action. These cells are gonna just explode.

 

Y621kvb.gif

MESOSCALE DISCUSSION 1379
NWS STORM PREDICTION CENTER NORMAN OK
0349 PM CDT SUN JUL 12 2015

AREAS AFFECTED...ERN SD...SW MN...FAR NW IA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 122049Z - 122215Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...SVR TSTMS CAPABLE OF DAMAGING WINDS...LARGE HAIL...AND
POTENTIALLY A TORNADO OR TWO ARE EXPECTED TO DEVELOP ACROSS PART OF
THIS REGION. WHILE SOME UNCERTAINTY EXISTS REGARDING THE TIMING OF
CONVECTIVE INITIATION...A WW WILL LIKELY BE NEEDED ONCE TSTMS DO
DEVELOP.

DISCUSSION...RECENT SATELLITE IMAGERY DEPICTS A SHORTWAVE TROUGH
MOVING THROUGH CNTRL SD. ASCENT FROM THIS SHORTWAVE IS CONTRIBUTING
TO THE ACCAS FIELD ALONG THE SD/MN BORDER AS WELL AS THE ELEVATED
TSTM ACTIVITY CURRENTLY ONGOING ACROSS WRN ND AND W-CNTRL MN.
SURFACE ANALYSIS ALSO REVEALS A TROUGH AXIS EXTENDING FROM A LOW
OVER SW MANITOBA THROUGH THE CNTRL DAKOTA. RECENT VISIBLE SATELLITE
IMAGERY HAS RECENTLY SHOWN AN INCREASE IN CU ALONG THIS BOUNDARY.
AIRMASS DOWNSTREAM OF THIS SURFACE BOUNDARY AND SHORTWAVE TROUGH IS
VERY UNSTABLE WITH TEMPERATURES IN THE 90S...DEWPOINTS IN THE MID
70S...AND MLCAPE ESTIMATED OVER 4000 J PER KG.

THERE IS STILL SOME UNCERTAINTY AS TO WHEN CONVECTIVE INITIATION
OCCURS OVER THE AREA...ESPECIALLY SINCE IT APPEARS SOME MODEST LARGE
SCALE HEIGHT RISES ARE IMPINGING ON THE AREA. HOWEVER...GUIDANCE IS
CONSISTENT THAT INITIATION DOES OCCUR. ONCE INITIATION
OCCURS...EXPLOSIVE TSTM DEVELOPMENT IS EXPECTED WITH STRONG UPDRAFTS
AND SUFFICIENT SHEAR LEADING TO AN INITIAL SUPERCELL MODE. AS A
RESULT...LARGE HAIL...DAMAGING WINDS AND TORNADOES ARE ALL
POSSIBLE.. TRENDS ACROSS THE REGION WILL BE MONITORED CLOSELY WITH
WW ISSUANCE LIKELY NEEDED TO COVER THE EXPECTED SEVERE THREAT ONCE
INITIATION APPEARS IMMINENT.

 

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AppsRunner

AppsRunner

Posted
Posted

As I said earlier, as if the wind potential alone isn't a big enough threat tomorrow, combine the extremely saturated ground from inches upon inches of rain and you'll likely have widespread damage with significant uprooted trees and downed power lines/power poles.

Although it's quite a different scenario, Fort Wayne had tons of tree damage during that excessive rain/wind event a couple weeks ago. I'd imagine the 80mph gusts IWX is mentioning wouldn't bode well for places like IKK and really the entire region where record rainfall is occurring

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Quincy

Quincy

Posted
Posted

Yeah...maybe this should have been a Tornado Watch instead, lol...

The interesting thing is that mesoanalysis indicates rather weak shear up there, on the order of 20kts or so in terms of bulk shear. Even low level helcity (0-1km) is fairly unimpressive with pockets of 50 m2s-2.

 

The environment in Siouxland is much more impressive, but there are concerns with initiation and storm coverage. If a storm were to get going near the IA/MN/SD border and remain discrete, that would have a very high likelihood of dropping a tornado. The environment is currently characterized by 40-50kts bulk shear and 4000-5000 Jkg-1 MLCAPE, but to go along with initiation concerns, LCLs are rather high at the moment. 

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Quincy

Quincy

Posted
Posted

I'm not sure if this has been mentioned for tomorrow and maybe it's the NAM being its good old self, but the 18z run appears to be keeping winds a bit more backed across central Illinois. Some rather extreme hodographs (PDS TOR via SHARPpy) by 01-03z, however that may be a bit skewed by a convective contamination as it develops a low over northern Illinois. 

 

No doubt that tomorrow as high-end potential, even if it's only with a few storms. Concur with other thoughts about a full-out tornado outbreak being unlikely, but the environment should favor significant forms of all severe hazards, including strong tornadoes.

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Quincy

Quincy

Posted
Posted

COD's launch from Wheaton, MN

Wind fields are decent, but some capping hanging on and those LCLs will need to come down a bit for a more robust tornado threat. Glad they got a balloon up. MPX is really too far east to give a good sampling of what will happen in the initiation environment.

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Thundersnow12

Thundersnow12

Posted
Posted

I'm not sure if this has been mentioned for tomorrow and maybe it's the NAM being its good old self, but the 18z run appears to be keeping winds a bit more backed across central Illinois. Some rather extreme hodographs (PDS TOR via SHARPpy) by 01-03z, however that may be a bit skewed by a convective contamination as it develops a low over northern Illinois. 

 

No doubt that tomorrow as high-end potential, even if it's only with a few storms. Concur with other thoughts about a full-out tornado outbreak being unlikely, but the environment should favor significant forms of all severe hazards, including strong tornadoes.

 

The 18z NAM did have a more southerly component to the sfc winds, deepens the sfc low 4mb in 3hrs between 21-0z

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Quincy

Quincy

Posted
Posted

Storm going there Sisseton but it's in the more mixed air with SW sfc flow

 

Winds are veering across eastern SD and far southwestern MN. I'm further doubting the tornado potential near the IA/MN border. Could still get a few storms, but even there, I think the HRRR is grossly overdone.

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