July 11-14 Severe Weather Event

[Powerball]

It has the event starting on the right front quadrant of the 500mb jet streak in N IN. With that solution, the enhanced risk area should shift east because the bow moves nearly due south. But 12z GFS has a blob of precip near the IL/IA/WI border at 12z, and it moves southeasterly throughout the day... the storm track would justify the current position of the enhanced risk area.

 

Can't wait to read some AFDs later on. I have no clue what to think at this point.

 

Watch the instability gradient. The stronger storms always track along the edge of it.

 

As things stand now, SW Ohio isn't in an awful spot. 

[ClicheVortex2014]

Watch the instability gradient. The stronger storms always track along the edge of it.

 

As things stand now, SW Ohio isn't in an awful spot. 

Yeah I'm worried about debris clouds/showers lasting too long. We've been screwed by that in the past 2 high risk events.

 

Indiana is sitting pretty right now. If I were a chaser, I'd be heading out for somewhere just south of Indianapolis

[Hoosier]

Looks like the models are still spitting out extreme dewpoints. Seems like SPC isn't buying the 80+ stuff but there's no reason not to believe it won't happen in some areas given the time of year and very wet ground.

[TimChgo9]

Nice big rain shield over W IL, moving ENE, or so, for the moment. Leading edge is at Route 39. ... Stretches from Peoria to Freeport. 

[snowlover2]

All these new Ohio people rooting for a N shift like its winter

Yeah Ohio posters are the only ones that do that. Being sarcastic if you didn't figure that out.

[brohnhdon]

I think we'd call that westerly

 

smells like a wishcast.

 

WNW-NW flow at 500mb and 250mb...and with the orientation of the instability gradient, there is no way something organized is moving due east. 

 

se1.gif

 

se2.gif

My bad, thanks for the correction. Even if it might seem like a wish cast, given I live in Ohio, it's what I would forecast regardless of my location. Regardless of upper level flow, the instability gradient will determine the track. By the models, that gradient is not where the current D3 would suggest. Also, I can't remember a ROF-type MCS moving east through Ohio, it's always from the north or northwest. Question: are outflow boundaries or upper flow more favored methods for locating initial storm development? Another thing that has me concerned is capping farther southwest.

[Brewers]

Definitely the best severe weather setup for E MN this year. Initial convection should take off across WC/SW MN before 00z as shortwave moves out of the Dakotas; likely growing upscale quickly. Current day 2 outlook looks good.

[Hoosier]

Placement of the day 3 outlook seems reasonable enough at this point.  You could maybe argue for some north/east expansion but that will depend on what happens prior to that.  I like the sharp gradient/drop off with western extent into IA/MO, as capping will become more of an issue with westward extent (unless the prior complexes go way farther south/west than forecast and don't give the cap a chance to strengthen).

[A-L-E-K]

All these new Ohio people rooting for a N shift like its winter

They need to pump the brakes

[chase_stormz]

These Ohio people driving me nuts smh. Quit wishcasting and enjoy the meteorological aspect of the summer wind event

[Tim from Springfield (IL)]

New Day 1 now has a small slight risk for Central Illinois (2% tor/15% wind/5% hail):

 

http://www.spc.noaa.gov/products/outlook/day1otlk.html

[Tim from Springfield (IL)]

If I remember correctly, St Louis had a severe thunderstorm blow through with little warning during a game a few years back. I feel like I remember there were some injuries due to flying debris and severe lightning, but don't quote me on that. I know there was extensive damage to some of the vendor carts and outdoor tarps.

 

That was the 7/19/2006 derecho, which originated in MN and finally dissapated in Arkansas.  I vividly remember that storm here in Springfield--coming just 4 months removed of the 3/12/06 F2s here in the south and east parts of the city:

https://en.wikipedia.org/wiki/Heat_wave_of_2006_derecho_series#St._Louis_area_derecho_event_.28July_19.2C_2006.29

(includes radar imagery of the storm)

 

Home video of the storm taken at Busch Stadium:

[Tim from Springfield (IL)]

If the models hold or slightly speed up, the MLB will have a nice test on monday. Hopefully the MLB and meteorologist advising them make the right calls. Cincy is going to be packed monday night. 

 

Unless the worst of the event holds off in the Quad Cities until at least tomorrow night, the PGA John Deere Classic this weekend could also be affected by severe weather.  Especially concerning what the models earlier in this thread were showing in the QCA.

[snowlover2]

They need to pump the brakes

[Tim from Springfield (IL)]

New MD out for central IL and hits at the possibility of a watch. 

http://www.spc.noaa.gov/products/md/md1362.html
 

Intense line of storms to my west especially between Macomb and Quincy, which could clip us here in SPI in the next few hours if it holds together.  Especially with hazy sunshine here now and already up to 81/72 after yet more morning rain.  Also already 90/73 in STL.

 MESOSCALE DISCUSSION 1362   NWS STORM PREDICTION CENTER NORMAN OK   1233 PM CDT SAT JUL 11 2015   AREAS AFFECTED...WRN AND CNTRL IL   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE    VALID 111733Z - 111900Z   PROBABILITY OF WATCH ISSUANCE...40 PERCENT   SUMMARY...AN ISOLATED WIND DAMAGE THREAT IS EXPECTED TO DEVELOP   ACROSS PARTS OF WRN AND CNTRL IL THIS AFTERNOON WHERE WW ISSUANCE   MAY BECOME NECESSARY ACROSS PARTS OF THE REGION.   DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A WARM FRONT EXTENDING   SEWD ACROSS SRN IA INTO WRN AND SRN IL WHERE SFC DEWPOINTS ALONG THE   BOUNDARY ARE IN THE 70S F. THE VERY MOIST AIRMASS IS CONTRIBUTING TO   MODERATE INSTABILITY...CURRENTLY ANALYZED ACROSS MOST OF MO AND FROM   WRN TO SRN IL. A LINE OF THUNDERSTORMS IS ONGOING IN WRN IL NEAR THE   MS RIVER ON THE NRN END OF THE STRONGER INSTABILITY. THIS CONVECTION   IS LOCATED JUST TO THE EAST OF A 30 TO 45 KT LOW-LEVEL JET MAXIMA   WHICH IS FORECAST TO SLOWLY STRENGTHEN THIS AFTERNOON...AIDING   CONVECTIVE DEVELOPMENT. SHORT-TERM MODELS INCLUDING THE HRRR MOVE   THE LINEAR SYSTEM ACROSS CNTRL IL OVER THE NEXT FEW HOURS. THE LINE   OF CONVECTIVE STORMS MAY TEND TO PROPAGATE SEWD FAVORING THE   STRONGER INSTABILITY LOCATED NEAR THE MS RIVER. IN ADDITION..THE   LINCOLN IL WSR-88D VWP SHOWS SUBSTANTIAL DIRECTIONAL SHEAR FROM THE   SFC TO 1 KM AGL WITH AMPLE SPEED SHEAR IN THE LOW TO MID-LEVELS.   THIS IS CONTRIBUTING TO 45 TO 50 KT OF 0-6 KM SHEAR WHICH WILL BE   FAVORABLE FOR ISOLATED SEVERE STORMS. WIND DAMAGE WILL BE POSSIBLE   WITH THE BETTER-ORGANIZED AND MORE PERSISTENT LINE-SEGMENTS. IF A   ROTATING STORM CAN DEVELOP...THEN HAIL WILL ALSO BE POSSIBLE.   ..BROYLES/HART.. 07/11/2015

[buckeye]

All these new Ohio people rooting for a N shift like its winter

 

well you know how it is, in places like IL models always lock in on the correct solution 3 days out, so you guys don't actually ever have to 'root' for a shift this way or that way.   So please just bear with us Ohio folk.   Thanks for your patience!

[Jim Marusak]

Definitely the best severe weather setup for E MN this year. Initial convection should take off across WC/SW MN before 00z as shortwave moves out of the Dakotas; likely growing upscale quickly. Current day 2 outlook looks good.

agreed. and as much as I have to admit i was thinking mod risk for STC/FBL/MSP/RST/LSE/AEL for d2, I could see holding that off until the 1630z d1 outlook tomorrow, when the last of the 12z data would be in (as 20z update would be near initiation time). But if the 18Z special soundings tomorrow, and there should be a couple for ABR/INL/MPX/OAX/GRB/DVN imho (and STC/DSM if they can dig out the equipment at SCSU and ISU), show it actually being close to the current NAM setup, then i would hope they would be willing to go PDS T-storm watch instead of normal t-storm watch in central/eastern MN, extreme western WI, and northeastern IA.

 

but time will tell.

[ClicheVortex2014]

These Ohio people driving me nuts smh. Quit wishcasting and enjoy the meteorological aspect of the summer wind event

[Quincy]

Looks like the models are still spitting out extreme dewpoints. Seems like SPC isn't buying the 80+ stuff but there's no reason not to believe it won't happen in some areas given the time of year and very wet ground.

The June 24 event had several stations in SW IA reporting 79-81 degree dews and if I remember correctly, the local WFOs were largely discounting the NAM guidance that was spitting out 80 dews.

[ClicheVortex2014]

agreed. and as much as I have to admit i was thinking mod risk for STC/FBL/MSP/RST/LSE/AEL for d2, I could see holding that off until the 1630z d1 outlook tomorrow, when the last of the 12z data would be in (as 20z update would be near initiation time). But if the 18Z special soundings tomorrow, and there should be a couple for ABR/INL/MPX/OAX/GRB/DVN imho (and STC/DSM if they can dig out the equipment at SCSU and ISU), show it actually being close to the current NAM setup, then i would hope they would be willing to go PDS T-storm watch instead of normal t-storm watch in central/eastern MN, extreme western WI, and northeastern IA.

 

but time will tell.

I'd be surprised if we don't get a moderate out of either day. I'd be pleased enough if the insane CAPE values verify... bonus points if we get a great sounding showing it.

[ClicheVortex2014]

Wow... IND's AFD is excellent. Definitely sounding like they're gonna get nailed. 

 

 

ACTIVE WEATHER PATTERN EXPECTED FOR THE ENTIRE SHORT TERM AS THE
REGION RESIDES IN A NORTHWEST FLOW REGIME ON THE PERIPHERY OF THE
BROAD RIDGE ALOFT. AS UPPER WAVES KICK UP AND OVER THE RIDGE...MUCH
OF THE GREAT LAKES AND OHIO VALLEY WILL BE IN THE FAVORED CORRIDOR
FOR MULTIPLE AND REPEATED IMPACTS FROM CONVECTIVE CLUSTERS CAPABLE
OF SEVERE WEATHER AND HEAVY RAINFALL.

THE MODEL SUITE IS IN GOOD AGREEMENT ON THE LARGE SCALE
FEATURES...BUT IMPACTS FROM MESOSCALE FEATURES SUCH AS OUTFLOW
BOUNDARIES AND SPECIFIC PLACEMENT OF THE INSTABILITY AND THERMAL
GRADIENTS WILL PLAY BIG FACTORS IN HOW AND WHERE THE CONVECTIVE
CLUSTERS EVOLVE. LOT TO DISCUSS THIS AFTERNOON. SUBTLE TIMING
DIFFERENCES STILL EXIST WITHIN THE VARIOUS MODEL RUNS WITH RESPECT
TO THE INDIVIDUAL WAVES ALOFT. WITH THAT BEING SAID...GENERAL
AGREEMENT EXISTS THAT SUPPORTS RENEWED CONVECTIVE DEVELOPMENT LATE
SUNDAY INTO SUNDAY NIGHT AND EARLY MONDAY FROM THE NORTHWEST...
FOLLOWED AGAIN ON MONDAY AFTERNOON AND EVENING THEN POSSIBLY AGAIN
ON TUESDAY.

CONVECTION WILL LIKELY STILL BE ONGOING IN PARTS OF THE AREA SUNDAY
MORNING AS THE OVERNIGHT STORMS TRACK SOUTHEAST. WILL BE NOTICEABLY
MORE HUMID AS DEWPOINTS SHOULD SURGE INTO THE LOWER 70S BY MIDDAY
SUNDAY AS STORMS DIMINISH. AS HEATING COMMENCES....EXPECT RENEWED
DEVELOPMENT SUNDAY AFTERNOON AND EVENING WITH POTENTIAL FOR
SCATTERED STRONG/SEVERE STORMS AS INSTABILITY LEVELS SURGE. EXPECT
DEVELOPMENT OF A STRONGER MCS IN THE UPPER MIDWEST LATE SUNDAY WHICH
WILL FLOW RIGHT DOWN INTO THE REGION...LIKELY SOMETIME AFTER
MIDNIGHT. WRF RUNS PICKING UP ON THIS FEATURE AS WELL AS THE NAM AND
OP GFS. THIS COMPLEX WILL LIKELY HAVE A DAMAGING WIND THREAT IN
ADDITION TO THE HEAVY RAIN/FLOODING POTENTIAL...AND SHOULD HAVE NO
TROUBLE MAINTAINING ITS INTENSITY AS A WESTERLY 850MB LOW LEVEL JET
FEEDS IT ALL NIGHT.

MONDAY REMAINS THE DAY WHERE THE MOST PARAMETERS APPEAR TO BE
ALIGNING FOR HIGHER CONFIDENCE IN A LARGER AND MORE WIDESPREAD
SEVERE WEATHER EVENT. MONDAY COULD ALSO BE ONE OF THOSE RARE DAYS
WHERE THE REGION IS IMPACTED TWICE BY SIGNIFICANT STORM
CLUSTERS...THE REMNANTS OF THE OVERNIGHT MCS IN THE MORNING FOLLOWED
BY ANOTHER ROUND DURING THE AFTERNOON AND EVENING. STRONGEST OF THE
WAVES ALOFT SET TO IMPACT THE REGION LATER ON MONDAY WITH A FAIR
AGREEMENT ON A STRONGER SURFACE REFLECTION ALONG THE REMNANT
BOUNDARY AS WELL...EVEN THOUGH THE DIFFERENT MODEL POSITIONS OF THE
SURFACE WAVE BY MONDAY EVENING VARIES FROM WESTERN LAKE ERIE TO THE
UPPER MISSISSIPPI VALLEY.

MODEL CONSENSUS CONTINUE TO THROW OUT STRONG AND VERY IMPRESSIVE
CAPE VALUES TO THE TUNE OF 3000-4000 J/KG MLCAPES WITH HIGHEST
VALUES OVER THE SOUTHWEST HALF OF THE FORECAST AREA BY MONDAY
AFTERNOON. WHILE THE NAM AND OP GFS IN PARTICULAR MAY BE SLIGHTLY
OVERDOING EXPECTED DEWPOINTS...STILL THINK LOW/MID 70S TDS WILL BE
COMMON AND THE HIGHER CAPE VALUES ARE SUPPORTED. IN ADDITION...BL
SHEAR VALUES ON THE ORDER OF 30-40KTS WITH THE CONTINUED INFLUENCE
OF A 40KT LOW LEVEL JET AND THE ARRIVAL OF AN UPPER LEVEL JET STREAK
PRESENTS A HIGHER CEILING FOR WIDESPREAD ROBUST CONVECTIVE
DEVELOPMENT. WITH A SURFACE WAVE IN THE AREA AND LIKELY A PLETHORA
OF OUTFLOW BOUNDARIES FROM EARLIER STORMS ENHANCING HELICITIES AS
WELL...ALL MODES OF SEVERE WEATHER WOULD BE IN PLAY ON MONDAY...
INCLUDING THE POTENTIAL FOR TORNADOES AND LARGE HAIL. AN EXTENSIVE
DAMAGING WIND THREAT REMAINS THE PRIMARY CONCERN ALONG WITH THE
HEAVY RAINFALL. ANALYSIS OF FAVORED CIPS ANALOGS SUPPORT THIS
THINKING AS WELL.

LIKELY TO SEE YET ANOTHER ROUND OF STORMS IMPACT THE REGION TUESDAY
AS THE UPPER TROUGH SHARPENS OVER THE EASTERN GREAT LAKES AND HELPS
TO MAINTAIN A NORTHWEST FLOW ALOFT ACROSS THE OHIO VALLEY. MODEL
SOUNDINGS AND OVERALL AVAILABLE INSTABILITY IS LOWER THAN MONDAY BUT
STILL MORE THAN SUFFICIENT FOR POTENTIAL ANOTHER CONVECTIVE CLUSTER
PRODUCING SEVERE WEATHER. WILL MAINTAIN 40-60 POPS OVER MUCH OF THE
REGION THROUGH THE BULK OF THE SHORT TERM.

THE HEAVY RAINFALL AND FLASH FLOODING ASPECT REMAINS A MAJOR CONCERN
THROUGH THE SHORT TERM CONSIDERING THE WET SOILS ALREADY ACROSS THE
FORECAST AREA. PRECIP WATER VALUES WILL REMAIN IN THE VICINITY OF 2
INCHES THROUGHOUT THE PERIOD...LIKELY ENHANCING IN EXCESS OF 2
INCHES AS CONVECTIVE CLUSTERS PASS THROUGH. AS STATED ABOVE IN THE
NEAR TERM SECTION...WE WILL ALMOST CERTAINLY NEED A FLASH FLOOD
WATCH BY SUNDAY OR SUNDAY NIGHT AT THE LATEST GOING FORWARD THROUGH
THE SHORT TERM PERIOD.

TEMPS...HIGHS THROUGH THE PERIOD WILL REMAIN HIGHLY DEPENDENT ON
TIMING AND LOCATION OF CONVECTION AND ASSOCIATED CLOUDS. FELT A MOS
BLEND WAS THE BEST APPROACH WITH HIGHS GENERALLY RANGING FROM THE
MID TO UPPER 80S. LOWER WABASH VALLEY MAY MAKE IT INTO THE LOWER 90S
AND WITH DEWPOINTS INTO THE 70S...MAY SEE HEAT INDICES IN SOUTHWEST
COUNTIES APPROACH 100F. LOWS WILL BE GENERALLY IN THE LOWER TO MID

 

[buckeye]

Wow... IND's AFD is excellent. Definitely sounding like they're gonna get nailed. Getting really excited for this event.

 

this is 100% anecdotal and I'm not a huge severe wx fan or follower, but I've often noticed over the last several years that when it comes to the OV and eastern MW, the more telegraphed and hyped a severe wx event is suppose to be, the more it tends to flop.   The most severe wx event I've experienced was the historic derecho of June 29-30 2012.   The wind damage was unreal in it's scope.  There was little if any warning that day about severe weather.   The second most severe event was the wind storm that was the remnants of hurricane Ike in September '09(?).   Again, not even a wind advisory the morning of.

[snowlover2]

Wow... IND's AFD is excellent. Definitely sounding like they're gonna get nailed. 

I would hope ILN's AFD looks similar to this.

[ClicheVortex2014]

this is 100% anecdotal and I'm not a huge severe wx fan or follower, but I've often noticed over the last several years that when it comes to the OV and eastern MW, the more telegraphed and hyped a severe wx event is suppose to be, the more it tends to flop.   The most severe wx event I've experienced was the historic derecho of June 29-30 2012.   The wind damage was unreal in it's scope.  There was little if any warning that day about severe weather.   The second most severe event was the wind storm that was the remnants of hurricane Ike in September '09(?).   Again, not even a wind advisory the morning of.

Yeah the June 29 derecho wasn't detected by the near-term models until ~6 hours before it actually happened. Given the circumstances, that's not too surprising.

 

Despite the absence of an upper level (or "jet stream") disturbance to encourage development, the Iowa thunderstorms grew and developed east into northern Illinois through the remainder of the morning as the moist southwesterly flow continued to impinge on the front. Storm development and intensity were enhanced by the presence of a deep "elevated mixed layer,"

 

http://www.spc.noaa.gov/misc/AbtDerechos/casepages/jun292012page.htm

 

Hurricane Ike was in 2007... we did have a high wind warning, but I don't blame you for not remembering that because not many people expected that. 

 

LOT doesn't sound too optimistic

300 PM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES THROUGH

TUESDAY NIGHT...THEN AGAIN LATER NEXT WEEK...HEAVY RAIN POTENTIAL

LATE SUNDAY NIGHT/MONDAY MORNING...HIGH TEMPS MONDAY AND THEN HIGH

TEMPS AGAIN NEXT FRIDAY/SATURDAY.

GUIDANCE HAS BEEN IN FAIR AGREEMENT OVER THE PAST 24 HOURS WITH

THUNDERSTORMS DEVELOPING WITH AN UPPER WAVE ACROSS THE MIDWEST

SUNDAY AFTERNOON INTO SUNDAY EVENING...WITH THIS ACTIVITY MOVING

SOUTHEAST INTO NORTHERN IL EITHER LATE SUNDAY EVENING OR INTO EARLY

MONDAY MORNING. WHILE THIS OVERALL TREND STILL LOOKS REASONABLE...

CONFIDENCE REMAINS LOW REGARDING TIMING/LOCATION. NEVERTHELESS...

DID BUMP POPS UP TO LIKELY DURING THIS TIME PERIOD AND INCLUDED

HEAVY RAIN MENTION. DEPENDING ON THE EVOLUTION OF THIS SYSTEM...

ALSO POSSIBLE FOR STRONG/SEVERE WINDS WITH ANY LINE OF STORMS

EARLY MONDAY MORNING.

ASSUMING CONVECTIVE ACTIVITY DOES AFFECT SOME OF THE AREA BY MONDAY

MORNING...THAT LOWERS CONFIDENCE FOR HOW SOON PRECIP ENDS...CLOUDS

CLEAR AND HOW MUCH TEMPS WARM MONDAY AFTERNOON AND HOW UNSTABLE

CONDITIONS BECOME. OPTED NOT TO MAKE MANY CHANGES FOR MONDAY...

LEAVING TEMPS GENERALLY MID 80S NORTH/UPPER 80S SOUTH...AGAIN ALL

DEPENDENT ON CLEARING TRENDS. AS FOR CONVECTIVE TRENDS...OPTED TO

KEEP JUST CHANCE POPS MONDAY AFTERNOON/EVENING. IF MORNING PRECIP

AND CLOUDS TAKE LONGER TO CLEAR WITH HIGHS NOT BEING REACHED UNTIL

LATE AFTERNOON...POSSIBLE MUCH OF THE AFTERNOON COULD END UP DRY.

CONVERSELY...FASTER CLEARING...HIGHER TEMPS AND POTENTIAL FOR NEW

THUNDERSTORMS BY MID AFTERNOON. WEAKER WIND FIELD MAY ALSO ALLOW A

LAKE BREEZE TO FORM...WHICH MAY AID THUNDERSTORMS DEVELOPMENT.

MONDAY WILL ALSO BE VERY HUMID WITH DEWPOINTS IN THE LOWER/MID 70S

WITH SOME UPPER 70S POSSIBLE.

A FRONTAL BOUNDARY WILL MOVE ACROSS THE AREA LATE MONDAY NIGHT INTO

TUESDAY...SHIFTING WINDS NORTH/NORTHEAST. HIGHS STILL IN THE 80S AND

WITH DEWPOINTS IN THE 70S POOLING AHEAD OF THIS FRONT WILL LIKELY BE

SUFFICIENT FOR SOME THUNDERSTORM DEVELOPMENT WHICH LOOKS MORE

SCATTERED FROM THIS DISTANCE. THIS ACTIVITY WOULD LIKELY DISSIPATE

WITH SUNSET TUESDAY EVENING. HIGH PRESSURE MOVING ACROSS THE

NORTHERN LAKES WEDNESDAY/WEDNESDAY NIGHT WILL THEN INCREASE THE

NORTHERLY GRADIENT OFF THE LAKE WITH HIGHS DROPPING BACK INTO THE

LOWER 80S...LIKELY ONLY 70S NEAR THE LAKE. WEDNESDAY LOOKS MAINLY

DRY WITH PERHAPS ISOLATED ACTIVITY IN THE AFTERNOON BUT AS ANOTHER

WAVE MOVES NORTHEAST AS THE UPPER RIDGE BUILDS BACK TOWARD THE

AREA WEDNESDAY NIGHT INTO THURSDAY...THERE WILL BE AT LEAST A

CHANCE OF THUNDERSTORMS.

 

[snowlover2]

I would hope ILN's AFD looks similar to this.

And it is.

 

 

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE WILMINGTON OH

412 PM EDT SAT JUL 11 2015

.SYNOPSIS...

AFTER A QUIET AND RAIN-FREE SATURDAY...THE WEATHER PATTERN TURNS

UNSETTLED AND ACTIVE AGAIN AS A WARM FRONT RETURNS NORTHWARD INTO

THE OHIO VALLEY AND IS INTERCEPTED BY WAVES OF LOW PRESSURE MOVING

OUT OF THE MISSISSIPPI VALLEY. THE RESULT WILL BE WAVES OF SHOWERS

AND THUNDERSTORMS BEGINNING LATER TONIGHT AND CONTINUING THROUGH

MID-WEEK. THE POTENTIAL FOR SOME STRONG TO SEVERE STORMS

EXISTS...AS WELL AS FLOODING RAINS DEPENDING ON THE TRACK OF THE

THUNDERSTORM CLUSTERS. IT WILL REMAIN MUGGY AND MILD...WITH PLENTY

OF CLOUDS AND STORM CHANCES KEEPING THE HOTTEST AIR OFF TO THE

WEST.

&&

.NEAR TERM /THROUGH TONIGHT/...

SATURDAY AFTERNOON VISIBLE SATELLITE LOOPS AND REGIONAL RADAR

MOSAICS ARE SHOWING A RARITY - A MOSTLY RAIN-FREE DAY OVER

INDIANA/OHIO/KENTUCKY AS A WEAK BUBBLE OF HIGH PRESSURE /1022 MB/

IS SITUATED OVER NORTHWEST OHIO AS OF 18Z. THE EFFECTIVE FRONTAL

BOUNDARY HAS BEEN SHOVED SOUTH/SOUTHWEST INTO SOUTHERN

ILLINOIS/KENTUCKY/TENNESSEE WITH LIGHT BOUNDARY LAYER FLOW OVER

THE ILN FORECAST AREA. MID 50S DEW POINTS - A RARITY OVER THE LAST

6 WEEKS - HAVE SPREAD INTO CNTL/NRN OH BUT AN ANOMALOUSLY MOIST

BOUNDARY LAYER LINGERS ALONG THE AFOREMENTIONED FRONT...AND 18Z

METARS SHOW DEW POINTS IN THE LOW-MID 70S POISED TO OUR SOUTHWEST

WITH TEMPERATURES IN THE UPPER 80S. ELEVATED WARM ADVECTION AND

VERY WEAK ELONGATED VORTICITY MAX IN 700-500MB LEVEL DRIVING SOME

SPRINKLES ACRS CNTL INDIANA. THESE MAY WORK INTO SERN IND/WRN

OH/NRN KY THROUGH EARLY EVENING BEFORE FALLING APART. HAVE

SPRINKLES IN THE FCST TO ACCOUNT FOR THIS FOR A FEW HOURS FROM 21Z

THRU 02Z.

18Z OBJECTIVE ANALYSIS SHOWS A DOMINANT SUBTROPICAL MID-LEVEL

RIDGE CENTERED OVER TX/LA RETROGRADING WESTWARD...AND A

DEVELOPING/SEASONABLY FAST QUASI-ZONAL FLOW ATOP THIS RIDGE ACROSS

THE CORN BELT INTO THE OHIO VALLEY WHERE FLOW WEAKENS A BIT DUE TO

THE PRESENCE OF SHORTWAVE RIDGING. A RATHER STRONG S/W TROUGH

EMBEDDED IN THIS FLOW OVER IA/IL IS DRIVING AN EVOLVING CONVECTIVE

CLUSTER IN WCNTL IL WITH THE RECENT TRENDS /BOTH OBSERVATIONALLY

AND IN HIGH-RES SHORT TERM GUIDANCE/ SUGGESTING THIS WILL

MOVE/DEVELOP ALONG THE SYNOPTIC FRONTAL ZONE IN ILL INTO SRN

IN/WRN KY THROUGH THIS AFTERNOON AND INTO THIS EVENING. AM BANKING

ON THE SWRN FLANK OF THIS PORTION OF THE MCS BECOMING DOMINANT

WITH BETTER INFLUX OF INSTBY AND THUS NET DEVELOPMENT WILL TEND TO

BE WEST OF OUR FORECAST AREA THROUGH THE EVENING.

HOWEVER...NORTHERN PORTIONS OF THE MCS MAY RIDE EAST INTO THE

FORECAST AREA AS DETAILED BELOW.

THIS SHORTWAVE OVER IA WILL PROGRESS EASTWARD INTO THE GREAT LAKES

TONIGHT AS THE RIDGE CONTINUES TO RETROGRADE WWRD....WITH THE S/W

NEAR DETROIT/TOLEDO BY SUNRISE ON SUNDAY. THIS ARE DISPARATE

SOLUTIONS ON HOW ROBUST THE LLJ/925-850MB MOISTURE TRANSPORT

MAGNITUDES WILL BE LATER TONIGHT IMMEDIATELY DOWNSTREAM OF THIS

S/W AS IT PUSHES INTO THE GREAT LAKES - SO HOW ROBUST THE ELEVATED

CONVECTION /MCS/ THAT CONTINUES TO GROW IN ILL/IND WILL BE REMAINS

IN QUESTION. HAVE PRETTY GOOD CONFIDENCE THAT COMBINATION OF S/W

DYNAMICS AND LOW LEVEL THERMODYNAMICS WILL BE PLENTY TO DRIVE A

SLOWLY WEAKENING AREA OF STORMS INTO THE WRN SIDE OF THE FORECAST

AREA AFTER MIDNIGHT /PROBABLY MOSTLY AFTER 08Z/ AND DROPPING

SOUTHEAST - AGAIN PROBABLY AFFECTING THE WRN/SWRN SIDE OF THE

FORECAST AREA /TRI-STATE AREA/ MORE THAN THE EAST/NORTHEAST. SO

EXPECT IT WILL BE RUMBLY/WET START TO SUNDAY FOR MANY IN OUR AREA

AND HAVE INCREASED RAIN CHANCES APPROPRIATELY IN THE

FORECAST.DON/T SEE A SEVERE THREAT HERE AS EXPECT STORMS WILL BE

ELEVATED ATOP A STABLE BOUNDARY LAYER NORTH OF SLOWLY RETURNING

WARM FRONT - BUT COULD SEE THE POTENTIAL FOR SOME ADVISORY-LEVEL

FLOOD ISSUES WITH HEAVIEST CORES DUE TO IMPRESSIVE MOISTURE

TRANSPORT AND GOOD ORTHOGONAL ORIENTATION OF THE LOW LEVEL JET TO

THE THERMAL RIBBON. 11.12Z NSSL-WRF...NCEP ARW-WRF...AND

EXPERIMENTAL 3KM NAMRR CONUS NEST ALL DEPICTING SOME HEAVIER RAIN

TOTALS POSSIBLE WITH THIS OVER SRN IND WHICH MAY INVOLVE OUR SWRN

PART OF OUR FORECAST AREA.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...

THE HIGHER CONFIDENCE ARRIVAL OF THE LATE SATURDAY NIGHT/SUNDAY

MORNING ELEVATED STORMS ONLY SERVE TO MUDDLE THE CONVECTIVE

EVOLUTION/DEVELOPMENTS ON SUNDAY. AM NOT COMFORTABLE WADING TOO

DEEP INTO THE WEEDS ON SEVERE/HEAVY RAIN POTENTIAL ON SUN

AFTN/EVENING BECAUSE OF WHAT SHOULD BE A RATHER EXTENSIVE

CLOUD/REMNANT RAIN AREA THAT HAS TO WORK THROUGH THE AREA SUNDAY

MORNING INTO EARLY AFTERNOON. THUS...I DON/T BUY INTO AN

AGGRESSIVE NORTHEAST PUSH OF THE LOW LEVEL FRONTAL ZONE TO OUR

SOUTHWEST. THINK FORECAST HIGHS COULD BE TOO WARM AND AM RUNNING

ON THE COOL SIDE OF GUIDANCE ALREADY. MID LEVEL HEIGHTS DO NOT

RISE AT ALL SUNDAY /PER NAM AND GFS/ SO IT/S GOING TO BE HARD TO

LIFT FRONTAL ZONE MUCH FURTHER FROM WHERE IT IS AT. DESPITE

THAT...CONTINUE MODERATE NWLY FLOW AND LOW LEVEL WARM ADVECTION

WILL LIKELY INITIATE CONVECTION ON OUTFLOWS FROM DECAYED MCS. THE

QUESTION BECOMES LOCATION AND INTENSITIES OF SAID CONVECTION.

ASSUMING AT LEAST MODEST DIABATIC HEATING OCCURS...TEMPS SHOULD

WARM TO NEAR 80F AND WITH THE ONGOING HIGH MOISTURE BOUNDARY LAYER

IT APPEARS THERE SHOULD BE ENOUGH LOW LEVEL FORCING FOR AT LEAST

SCATTERED CONVECTION FOCUSED ON THE DIURNAL MAXIMUM -- PROBABLY

INITIALLY OVER INDIANA WHICH WILL DRIFT INTO THE FORECAST AREA IN

TIME. FORECAST SOUNDINGS VARY MARKEDLY IN INSTBY /AGAIN DEPENDENT

ON DEGREE OF INFLUENCE FROM MORNING CONVECTION/ BUT THERE IS A

BETTER AGREEMENT THAT FLOW FIELDS WON/T BE PARTICULARLY STRONG

WITH MID LEVEL WINDS AROUND 25KT. SO SHEAR IS MARGINAL FOR

ORGANIZED STORMS...AND INSTBY IS LIKELY TO BE MAXIMIZED IN INDIANA

WHERE EWRD EXTENSION OF PLAINS-BASED MID-LEVEL LAPSE RATE PLUME IS

LOCATED. SO BETTER CHANCE OF A STRONG/SEVERE STORM IN THE WEST VS.

THE EAST SIDE OF THE FORECAST AREA IN THE AFTN/EVENING...AND

DETAILS BEYOND THAT TOO MUDDY TO DISCERN AT THIS TIME.

HAVE A LITTLE MORE CONCERN ON LATER SUNDAY NIGHT INTO MONDAY AS

A MORE APPRECIABLE EXTENSION OF THE PLAINS-BASED EML /700-500 MB

LAPSE RATE > 7.5 C/KM/ IS ADVECTED EAST INTO ILL/IND AND

EVENTUALLY OHIO DOWNSTREAM OF A STRONGER SHORTWAVE TROUGH CRESTING

THE TOP OF THE SUBTROPICAL RIDGE AND FASTER NWLY FLOW REGIME OVER

THE GREAT LAKES. THIS CREATES A WINDOW OF OPPORTUNITY FOR VERY

HIGH POOL OF BOUNDARY LAYER MOISTURE /DEW POINTS IN LOW-MID 70S/

TO BE ADVECTED EAST UNDER THESE LAPSE RATES INTO WHAT SHOULD BE A

STRONGER DEVELOPING WARM FRONT THAT WILL BE CONVECTIVELY

REINFORCED SOMEWHERE IN ILL/IND/KY. THIS PROMOTES A FAVORED

OVERALL SETUP FOR SUNDAY NIGHT /LLJ AND SHORTWAVE INDUCED

CONVECTION/ TO DEVELOP OVER THE WESTERN CORN BELT AND RIDE THE

WARM FRONT AND DEVELOPING EXTREME INSTBY GRADIENT ALONG THIS

BOUNDARY. THE CIPS ANALOGS FOR THE CORN BELT VALID MONDAY HAVE

SHOWN A FAIR SHARE OF HIGHER-END OF FORWARD- PROPAGATING DAMAGING

WIND EVENTS AS POTENTIAL OUTCOMES OF A PATTERN LIKE THIS - AND

THUS ATTENTION IS RAISED ON MONDAY/MONDAY NIGHT AS EVOLUTION OF

CONVECTION TO OUR NW SUNDAY NIGHT/MONDAY MORNING MAY IMPACT THE

FORECAST AREA. TIMING/LOCATION HAVE ALL KINDS OF UNCERTAINTY...BUT

FOCUSING ON THE PATTERN ITSELF...THE FLOW OVERLAP /40KTS AT 500MB/

ATOP EXTREME INSTABILITY...A LOW LEVEL BOUNDARY...AND A STRONG

SHORTWAVE BEARS CONSIDERABLE WATCHING FOR ALL MODES OF SEVERE WX

ON MONDAY. AGAIN - HAVE A LOT OF CONCERN THAT REPEAT CONVECTION

WILL KEEP THE FOCUS ON SOUTH/WEST SIDE OF FORECAST AREA...AND

PERHAPS EVEN TO THE SOUTHWEST OF THAT...SO WE/LL HAVE TO EVALUATE

WITH CAUTION ON WHAT CONCLUSIONS ARE DRAWN ON THE POTENTIAL. THE

HIGHEST THREAT/IMPACTS MAY BE PINNED OVER INDIANA/ILLINOIS DUE TO

SEVERAL DAYS OF MCS ACTIVITY. KEPT TEMPS MONDAY AGAIN ON THE COOL

SIDE OF GUIDANCE WITH THE IDEA THE UPSTREAM CONVECTION/DEBRIS

CLOUDS WILL PLAY A ROLE.

THROUGH ALL OF THIS...WE ARE LIKELY TO EVOLVE ONCE AGAIN INTO A

HYDRO/HEAVY RAIN THREAT GIVEN WHAT SHOULD BE SEVERAL CHANCES AT

MCS/STORM CLUSTERS. IN NWLY FLOW WITH NW-SE RUNNING SYNOPTIC

FRONTS AND OUTFLOW BOUNDARIES...WON/T TAKE MUCH TO SET UP A SHORT

TERM/STORM SCALE LOCALIZED FLOOD THREAT FOR AREAS HIT REPEATEDLY.

[jojo762]

Where did LOT get that thinking from, basing off of most model guidance? Lol. Besides being pessimistic due to the recent history of nearly every high-potential event, save maybe a few, have turned out to be trash compared to what they were once thought to be. With a large severe MCS barreling through the Midwest during the early/late morning I guess I could see it.. But still would seem that where ever the OFB from this ends up being and areas south would have high-end potential with all severe hazards possible.

[Quincy]

Have to wonder about storm mode tomorrow. Some of the NAM (12z and 18z) forecast soundings are pretty extreme in southern Minnesota early tomorrow evening. I'm very cautious about using NAM forecast radar based on performance this warm season, but it is showing only a few cells through 02z/03z across southern MN and western IA. Assuming cells can fire and remain at least semi-discrete in this environment (S MN and perhaps much of IA), look out:

 

That would spell much more of a tornado threat than I had first thought.

[HillsdaleMIWeather]

IWX feel's storms will impact there whole CWA, says a significant event for everyone is possible. However exact location's are not good enough to pin-point, citing it could end up north or south of the current guidance. 

[hoosierwx]

LMK says forecaster beware:

 

Northwest flow is notorious for mesoscale convective complexes and
systems (MCC, MCS) though, which in turn are notorious for creating
large cirrus shields that block out the sun, limiting sunshine,
diurnal heating, and destabilization. In other words, they`re good
for busting forecasts. Soooooo, the moral of this story is that
you`ll want to check the forecast each day for changes resulting
from storms upstream in Iowa, Illinois, and Indiana.

 

[RCNYILWX]

Where did LOT get that thinking from, basing off of most model guidance? Lol. Besides being pessimistic due to the recent history of nearly every high-potential event, save maybe a few, have turned out to be trash compared to what they were once thought to be. With a large severe MCS barreling through the Midwest during the early/late morning I guess I could see it.. But still would seem that where ever the OFB from this ends up being and areas south would have high-end potential with all severe hazards possible.

All I can say is that forecaster tends to be on the conservative side when it comes to writing about severe threats.