July 8-10 Severe Threat

[Hoosier]

Looks like a few days of severe wx coming up.

[andyhb]

12z GFS looked quite interesting for the western part of region on Tuesday. Pretty active jet pattern overall for this time of year.

[Hoosier]

12z GFS looked quite interesting for the western part of region on Tuesday. Pretty active jet pattern overall for this time of year.

Yeah, that's some pretty good low level shear especially for July.

[TimChgo9]

Been watching this for the last few days. The Supercell Index for Iowa really gets going on Wednesday, according to the latest GFS run. Seems the heavy rain avoids NE IL for the most part.

[Stebo]

All 3 local offices DTX/GRR/IWX talking up this potential especially if it comes during the afternoon on Wednesday locally.

 

DTX

 

 

CONSENSUS AMONG THE 12Z SUITE REMAINS STRONG THAT A MORE ORGANIZED
THUNDERSTORM/SEVERE THREAT WILL PRESENT ITSELF IN THE GREAT LAKES
REGION TUESDAY NIGHT OR WEDNESDAY AS A POTENT WAVE SEEN NEAR THE
ALEUTIAN ISLANDS THIS MORNING IS PROGGED TO HAVE AN OPPORTUNITY TO
PHASE WITH NORTHERN STREAM ENERGY OVER SOUTH-CENTRAL CANADA TUES/WED.

 

GRR

 

 

LOOKING LIKE AN ACTIVE WEEK WITH THUNDERSTORM THREATS ON MON THROUGH
WED. OVERALL PATTERN IS SHIFTING WITH THE EAST COAST BLOCKING RIDGE
FLATTENING AND RELOCATING WESTWARD OVER THE MS VALLEY BY MID WEEK.
MEANWHILE SEVERAL ENERGETIC SHORTWAVES WILL BEGIN TO RACE WEST TO
EAST ACROSS THE NORTHERN TIER AND SOUTHERN CANADA. GIVEN THIS
SCENARIO... PREFER THE FLATTER MORE PROGRESSIVE ECMWF OVER GFS
ESPECIALLY LATER IN THE WEEK.

ECMWF HAS BEEN CONSISTENT LAST FEW RUNS A CLUSTER OF EARLY MORNING
STORMS (MCS) AFFECTING LOWER MICHIGAN MONDAY MORNING AS SHORTWAVE
NOW MOVING INTO WASHINGTON STATE KICKS THROUGH THE REGION IN
INCREASINGLY WESTERLY UPPER LEVEL FLOW. THIS SEEMS REASONABLE AS
GOOD PRESSURE FALLS SHOULD OCCUR IN THE LEE OF ROCKIES AS THE WAVE
MOVES EAST ON SUNDAY AND THOSE WILL IN TURN ENERGIZE LOW LEVEL JET
PROVIDING PLENTY OF LOW LEVEL FUEL INJECTION LATE SUNDAY NIGHT AND
INTO MONDAY MORNING FOR DEVELOPING CONVECTION.

THE NEXT AND STRONGER WAVE MOVES THROUGH LATE TUE INTO WED WITH WHAT
IS LOOKING TO BE ALMOST THE WHOLE PACKAGE IN TERMS OF SEVER WEATHER
POTENTIAL. STRONG UPPER DIVERGENCE WILL COUPLE WITH STRONG LOW LEVEL
WIND FIELDS AND MOISTURE FLUX CONVERGENCE TO PRODUCE STRONG TO
SEVERE STORMS WITH HEAVY RAINFALL POTENTIAL ACROSS MOST OF SOUTHWEST
MICHIGAN. THE ONLY ISSUE WOULD BE TIMING WHICH AT THIS POINT LOOKS
LIKE IT MIGHT BE DURING THE EARLY MORNING HOURS WED VERSUS PEAK
AFTERNOON HEATING... WHICH WOULD LIMIT THE SEVERE POTENTIAL... A
GOOD THING.

 

IWX

 

 

WILL HOLD W/PRIOR HIGHEST CHC POPS IN TUE-WED PD IN PREFERENCE TO
MODEL IMPLIED PROGRESSION OF MOST SIG SW TROUGH ACRS THE THE NRN
PLAINS/NRN LAKES. OTRWS SUN-MON PD MORE VEXING GIVEN WK WRLY LL FLW
AND LIKELY SUBSIDENT SINK ALG WRN PERIPHERY OF DEPARTING MID LVL
TROUGH SUN. SHRT RANGE HIGHRES CONSENSUS WOULD ELUCIDATE A DRIER
SLANT TO GOING FCST AND HAVE GENERALLY CUT POPS THROUGH MON AM.
AFT THAT...A SUBSTANTIAL W-E LL THETA-E RIDGING XPCD TO DVLP THROUGH
THE SRN LAKES DOWNSTREAM OF LEE SIDE CYCLONE MON AFTN/NIGHT INVOF OF
FAIRLY VIGOROUS LLJ.

[Stebo]

The morning updates continue the theme from yesterday afternoon from DTX/GRR/IWX of talking up Wednesday

 

DTX

 

 

ZONAL FLOW ASSOCIATED WITH THE TRANSITION OUT OF LONG WAVE
AMPLIFICATION WILL CARRY THE UPPER LOW INTO THE EASTERN GREAT LAKES
BY MONDAY. THIS PROCESS WILL MAINTAIN AN ACTIVE RAIN PATTERN BUT
CHANGE THE CHARACTER TO ONE OF MCS POTENTIAL. REMNANTS OF CENTRAL
PLAINS MCS DEVELOPMENT COULD BRUSH LOWER MICHIGAN AS SOON AS MONDAY
BUT POTENTIAL WILL BE GREATER LATE MONDAY NIGHT INTO TUESDAY AS A
STRONGER LOW LEVEL JET WILL BE POSSIBLE OVER THE PLAINS STATES BY
THEN. SURFACE TROUGH DEVELOPMENT IN THE LEE OF THE ROCKIES WILL BE
FOSTERED BY THE ZONAL FLOW ALOFT AND A QUICK TRANSITION BACK TO AN
AMPLIFYING LARGE SCALE PATTERN. GLOBAL MODEL SOLUTIONS LOOK GOOD IN
THIS REGARD AS ANY KIND OF ZONAL WESTERLY FLOW IS NOT A STABLE
CONFIGURATION. THE NEW MODEL RUNS ARE THEN IN GOOD AGREEMENT WITH
THE DEPICTION OF A STRONG UPPER LEVEL TROUGH DEVELOPING OVER
NORTHERN ONTARIO BY WEDNESDAY. THIS SYSTEM HAS THE POTENTIAL TO
SUPPORT A STRONG SURFACE COLD FRONT FOR THIS TIME OF YEAR AND DRIVE
IT INTO THE MID SUMMER AIR MASS OVER LOWER MICHIGAN WEDNESDAY INTO
WEDNESDAY NIGHT. THE STRONG WIND FIELD ASSOCIATED WITH THIS SYSTEM
ALONG WITH MORE THAN ADEQUATE INSTABILITY WILL MAKE ORGANIZED
CONVECTION AND SEVERE WEATHER POSSIBLE BEFORE COOLER AND LESS HUMID
AIR SETTLES IN FOR THE END OF THE WEEK.

 

GRR

 

 

BEST CHANCE OF RAIN IN THE EXTENDED STILL LOOKS TO BE TUESDAY INTO
WEDNESDAY AS UPPER TROUGH AXIS AND SFC LOW MOVES THROUGH. MODELS
ARE IN DECENT AGREEMENT WITH THE GFS HAVING TRENDED TO THE MORE
AMPLIFIED TROUGH SHOWN BY THE ECMWF. PLENTY OF MOISTURE AVAILABLE
AND MCS DEVELOPMENT IS POSSIBLE TUESDAY NIGHT INTO WEDNESDAY MORNING
WITH HEAVY RAIN THREAT. SEVERE WEATHER POSSIBLE AT THAT TIME AS WELL
WITH DEEP LAYERED SHEAR SUFFICIENT FOR STRONG TO SEVERE STORMS
ESPECIALLY ACROSS THE NORTHERN FORECAST AREA.

 

IWX

 

 

THE LOCAL AREA WILL BECOME SITUATED ON THE SOUTHERN FRINGE OF ZONAL
WESTERLIES MONDAY THROUGH WEDNESDAY...IN THE VICINITY OF A WEST TO
EAST ORIENTED FRONTAL BOUNDARY/LOW LEVEL THETA-E RIDGE DRAPED FROM
IOWA TO THE SOUTHERN GREAT LAKES. EXPECT THAT MORE ORGANIZED
CONVECTION WILL FOCUS WNW OF THE AREA MONDAY AS WEAK SHORTWAVES
INTERACT WITH A DEVELOPING LLJ. FLOW LOOKS RELATIVELY WEAK MONDAY
INTO MONDAY NIGHT WHICH SHOULD MITIGATE THE SEVERE POTENTIAL AND MCS
MAINTENANCE. HOWEVER...SHORTWAVES ENHANCED FROM UPSTREAM CONVECTION
AND SUBSTANTIAL INSTABILITY GRADIENT IN PLACE MAY BE ENOUGH TO FORCE
AFTERNOON PULSE/MULTICELL TYPE CONVECTION IN AN INCREASINGLY
UNSTABLE/MOIST AIRMASS. THUNDERSTORM CHANCES AND THE SEVERE THREAT
INCREASE TUESDAY INTO WEDNESDAY AS FLOW/SHEAR INCREASES (ESPECIALLY
TUESDAY NIGHT/WEDNESDAY) UNDER A MORE PRONOUNCED SHORTWAVE DIGGING
TOWARD ONTARIO AND THE NORTHERN GREAT LAKES.

[TimChgo9]

Tuesday is looking like the day for NE IL and most of the rest of N IL, as well as S WI. 06z GFS iis showing high CAPE numbers over a good chunk of the region especially late Tuesday afternoon. GFS also showing about 2" of rain as well. Going to keep watching this run to run

[nwohweather]

If this means a few hours of sunshine I'm all for it. It's like Seattle here with all this rain, just keeps pouring daily

[Minnesota Meso]

Based on what transpired today, Saturday 07/06, I would pay close attention to the ECMWF and the GEM looking out the next few days.  The NCEP model suites were absolutely horrible in regards to severe chances in the Upper Mississippi Valley today.  The GEM and the Euro had a much better handle on how things would play out.  As a matter of fact the GEM was slightly better than the Euro.

[TimChgo9]

GFS wants to keep the rain ouf of NE IL at least.  Last 2 runs of the GFS keep the heavy rain north and east, and cut the PW from 2.2" to about 1.25" or so. 

 

Looks like S. WI gets a decent shot at some storms on Tuesday, all that activity stays north of the IL/WI line.....

[Chicago WX]

Probably time for those in NE IL to punt. High and dry. GFS is always right, always...

 

 

 

EDIT: sarcasm for those that can't figure it out.

[Hoosier]

If there's one thing that was made for high-res models and nowcasting, it's convection. Well, that and LES.

[Chicago WX]

If there's one thing that was made for high-res models and nowcasting, it's convection. Well, that and LES.

 

Absolutely. And watching how things set up in the "very" short range. I'm not sure that any model will do well in the "medium range" with forecasting convection. Seems that way to me anyway.

[Thundersnow12]

0z NAM. Iowa. Tuesday

[TimChgo9]

Absolutely. And watching how things set up in the "very" short range. I'm not sure that any model will do well in the "medium range" with forecasting convection. Seems that way to me anyway.

 

I am figuring things will change again, that's why I have pretty much been watching run-to-run with this, just to see the changes, and see how much things change through each run.

[Chicago Storm]

I'll be out in far NW. IL Mon-Thurs.

 

Tues is looking good out that way and for surrounding areas, for some decent action.

[tornadotony]

Tuesday looks like a serious day for the I-80/I-88 corridors.

[andyhb]

0z NAM. Iowa. Tuesday

 

72 hrs out, but impressive...

[andyhb]

New D3:

...CNTRL/NRN PLAINS THROUGH UPPER MS VALLEY AND GREAT LAKES...   MAIN COMPLICATING FACTOR THIS FORECAST IS POTENTIAL FOR WIDESPREAD   CONVECTION TO BE ONGOING EARLY TUESDAY. MCS MAY BE IN PROGRESS FROM   ND INTO NRN MN AND FARTHER SOUTH FROM IA INTO THE SRN GREAT LAKES OR   NRN OH VALLEY WITHIN A BROAD ZONE OF WARM ADVECTION. THIS ACTIVITY   SHOULD CONTINUE EAST ALLOWING POTENTIAL FOR THE UPSTREAM BOUNDARY   LAYER TO DESTABILIZE. WHILE SOME CONVECTIVE DEBRIS MIGHT LINGER A   PORTION OF THE DAY...AT LEAST PARTIAL CLEARING SHOULD DEVELOP FROM   THE WEST. A BROAD FETCH OF MULTI-DAY SLY WINDS AND   EVAPOTRANSPIRATION WILL CONTRIBUTE TO UPPER 60S DEWPOINTS IN   PRE-FRONTAL WARM SECTOR...WHILE PLUME OF STEEPER LAPSE RATES ADVECT   EWD ABOVE THE MOIST AXIS. ASSUMING THE EARLY CONVECTION IS NOT TOO   WIDESPREAD AND CONTINUES EAST...POTENTIAL WILL EXIST FOR A RESERVOIR   OF STRONG INSTABILITY TO DEVELOP FROM ERN NEB...SERN SD...SRN MN   INTO IA WITH MLCAPE FROM 2000-3000 J/KG POSSIBLE.   STORMS SHOULD REDEVELOP DURING THE AFTERNOON ALONG RESIDUAL   PRE-FRONTAL OUTFLOW BOUNDARIES AND SEWD ADVANCING COLD FRONT. THIS   REGION WILL EXIST WITHIN BELT OF MODERATE WLY FLOW AOA 500 MB WITH   30-45 KT EFFECTIVE SHEAR SUPPORTIVE OF ORGANIZED STORMS INCLUDING   SUPERCELLS AND LINES WITH BOWING SEGMENTS. DAMAGING WIND AND LARGE   HAIL WILL BE THE MAIN THREATS...BUT A CONDITIONAL THREAT WILL ALSO   EXIST FOR ISOLATED TORNADOES...ESPECIALLY OVER THE UPPER MS VALLEY   REGION.   ..DIAL.. 07/07/2013

[Thundersnow12]

Flash flooding going to be a problem with any storm/MCS

 

 

[cyclone77]

Unlike the ring of fire event from a few weeks back, this is looking more like a one and done type of setup.  Tue evening looks pretty good for Iowa/Illinois/Wisconsin.  Wednesday for areas further east.  Thinking SPC may be a bit too far west with their day3 based on what I'm seeing.  I would chop off the western portion of the 30% and extend it further east through northern IL/southern WI.  Still a ways to go to this event so it really doesn't matter. 

[Chinook]

Hey Lakes/Ohio Valley people. I will be driving I-80 from Colorado to Ohio in the next two days, and possibly chasing some storms on Tuesday in Iowa/Illinois. (I won't attempt to do a chase in Chicago metro)  Does anybody want to nowcast for me, and call me on the phone?  I won't be able to make very good chasing (and/or storm-avoiding) decisions without some internet-friendly rest stops or a nowcaster helping me. Part of the reason I want to do this is to avoid large hail. Definitely don't want hail+Chicago traffic.

[Chinook]

Nice CAPE and helicity on Tuesday

 

[Castaway]

Hey Lakes/Ohio Valley people. I will be driving I-80 from Colorado to Ohio in the next two days, and possibly chasing some storms on Tuesday in Iowa/Illinois. (I won't attempt to do a chase in Chicago metro)  Does anybody want to nowcast for me, and call me on the phone?  I won't be able to make very good chasing (and/or storm-avoiding) decisions without some internet-friendly rest stops or a nowcaster helping me. Part of the reason I want to do this is to avoid large hail. Definitely don't want hail+Chicago traffic.

In my personal opinion and I might be wrong, but I dont think there's going to be an alarming hail event here in chicago. Just a hunch.

But we'll see tomorrow night how things are shaping up. IMO its still kinda early to make bets on how things are going to be.

I really hope to see some decents storms. Its been really quiet in the chicago area. But definently wouldnt want to see golfball-softball size hail here. Let that stay out in more rural areas with less cars on the street. Goes without saying.

Im really looking forward to this. Tomorrow night/tuesday cant come soon enough.

I'm near i-88 and 290 by the way.

[andyhb]

Interesting that the GFS seems to be biting on a more prominent lead wave/surface low leading to greater threat further east in Northern IL and Southern WI (perhaps eastward across Lake MI later on). The second s/w then comes in and may initiate another round back in IA later on.

 

GFS also has a strong LLJ response (40-50 kts at 850 mb).

[harrisale]

Interesting that the GFS seems to be biting on a more prominent lead wave/surface low leading to greater threat further east in Northern IL and Southern WI (perhaps eastward across Lake MI later on). The second s/w then comes in and may initiate another round back in IA later on.

 

GFS also has a strong LLJ response (40-50 kts at 850 mb).

 

LLJ really ramps up Tuesday in the overnight. Shame that this didn't pass over during the day, just not enough time to build instability in ON. MI may get a nice light show overnight with leftover daytime instability. Seems as though areas further east than ON will see stronger storms on Wednesday.

[andyhb]

Well then...Madison, WI at 18z Tuesday from the 00z NAM. That said, overnight convection from the previous night is obviously going to be a concern as the D3 earlier highlighted.

 

[Brewers]

The 00z NAM and GFS look fun for S WI Tues. Lower level shear looks pretty good on both models, NAM has better backing winds with height however.

[andyhb]

The 00z NAM and GFS look fun for S WI Tues. Lower level shear looks pretty good on both models, NAM has better backing veering winds with height however.

 

FYP.

[Brewers]

A broad area of 30% probability stretching from  lower MI back into IA on the new day 2.

 

 

SPC AC 080600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT MON JUL 08 2013

VALID 091200Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL AND NRN PLAINS
INTO THE MID-UPPER MS VALLEY AND GREAT LAKES...

...SYNOPSIS...

EXPANSIVE UPPER RIDGE WILL PERSIST OVER THE SRN TWO THIRDS OF THE
U.S. TUESDAY WITH BELT OF STRONGER WLYS OVER THE NRN TIER STATES. A
LOW AMPLITUDE SHORTWAVE TROUGH EMBEDDED WITHIN THIS BELT OF STRONGER
FLOW WILL MOVE FROM ERN MT EARLY TUE TO THE WRN GREAT LAKES BY 12Z
WED. A VORT MAX NOW OVER THE GREAT BASIN AREA WILL CONTINUE THROUGH
THE NRN PERIPHERY OF THE UPPER RIDGE...LIKELY REACHING THE UPPER MS
VALLEY AREA EARLY TUESDAY AND SUBSEQUENTLY CONTINUING THROUGH THE
GREAT LAKES DURING THE DAY.

AT THE SFC A QUASI-STATIONARY FRONT /PORTIONS OF WHICH MAY BE
CONVECTIVELY REINFORCED/ WILL LINGER FROM THE GREAT LAKES WWD
THROUGH IA AND NEB. THE NRN STREAM SHORTWAVE TROUGH WILL PROVIDE THE
IMPETUS FOR A COLD FRONT TO ACCELERATE SEWD THROUGH THE NRN/CNTRL
PLAINS AND UPPER MS VALLEY. BY THE END OF THE PERIOD THIS FRONT IS
FORECAST TO EXTEND FROM THE WRN GREAT LAKES SWWD THROUGH KS.

...CNTRL/NRN PLAINS THROUGH UPPER MS VALLEY AND GREAT LAKES...

GREAT LAKES AREA...AT LEAST A COUPLE OF MCSS WILL LIKELY BE ONGOING
EARLY TUESDAY INCLUDING PORTIONS OF ND INTO NRN MN AND ANOTHER
FARTHER SOUTH ACROSS PORTIONS OF IA AND SRN MN. THE IA MCS WILL
EXIST IN ASSOCIATION WITH THE LEAD /PARTIALLY CONVECTIVELY ENHANCED/
VORT MAX AND ITS ATTENDANT STRONGER WIND FIELDS. CURRENT
OBSERVATIONS SHOW RICH LOW-LEVEL MOISTURE ALREADY IN PLACE OVER THE
MID MS VALLEY AND GREAT LAKES REGION WITH UPPER 60S TO AROUND 70
DEWPOINTS. SOME UNCERTAINTY EXISTS REGARDING THE DEGREE OF
DOWNSTREAM DESTABILIZATION OVER THE GREAT LAKES GIVEN POTENTIAL FOR
AREAS OF WIDESPREAD CLOUDS. HOWEVER WITH RICH MOISTURE IN
PLACE...EVEN MODEST DIABATIC WARMING OF THE BOUNDARY LAYER WILL
SUPPORT MODERATE INSTABILITY WITH 1500-2000 J/KG MLCAPE POSSIBLE
FROM WI INTO MI. POTENTIAL WILL EXIST FOR STORMS TO INTENSIFY AS THE
MCV AND ONGOING MCS INTERACT WITH THE DESTABILIZING ATMOSPHERE.
STRONGER VERTICAL SHEAR ACCOMPANYING THE MCV WILL SUPPORT ORGANIZED
STORMS INCLUDING BOWING SEGMENTS AND EMBEDDED SUPERCELLS WITH
DAMAGING WIND...LARGE HAIL AND PERHAPS A COUPLE TORNADOES. A
CONDITIONAL RISK ALSO EXISTS FOR A MORE WIDESPREAD DAMAGING WIND
EVENT.

MID MS VALLEY AND CNTRL PLAINS AREA...THE MORNING STORMS SHOULD
CONTINUE EAST WITH CLEARING FROM THE WEST ALLOWING THE UPSTREAM
ATMOSPHERE TO BECOME STRONGLY UNSTABLE...ESPECIALLY FROM ERN
NEB...NERN KS INTO IA WHERE PLUME OF STEEP LAPSE RATES SHOULD
OVERLAP THE WRN EDGE OF RICHER LOW-LEVEL MOISTURE. SHORTWAVE RIDGING
IN WAKE OF THE LEAD VORT MAX AND WARM ADVECTION ALOFT MAY CAP THE
BOUNDARY LAYER AND DELAY INITIATION UNTIL LATE AFTERNOON WHEN
CONVECTIVE TEMPERATURES WILL LIKELY BE REACHED AND STORMS WILL
PROBABLY DEVELOP ALONG THE FRONT FROM ERN NEB INTO KS AND ALSO
FARTHER EAST INTO IA ALONG THE CONVECTIVELY ENHANCED STALLED
BOUNDARY. VERTICAL SHEAR FROM 30-40 KT WILL SUPPORT SUPERCELLS FROM
NEB INTO IA AND EXTREME NRN MO...BUT WITH MULTICELLS MORE LIKELY IN
THE WEAKER SHEAR ENVIRONMENT FARTHER SOUTH ACROSS KS. LARGE HAIL AND
DAMAGING WIND WILL BE THE MAIN THREATS.

MN INTO NRN WI...POTENTIAL EXISTS FOR THE ATMOSPHERE TO DESTABILIZE
WITH MODERATE INSTABILITY EAST AND SOUTH OF ONGOING MCS FROM CNTRL
AND SRN MN INTO NRN WI. THE MCS WILL LIKELY CONTINUE EWD DURING THE
DAY...EVENTUALLY MOVING INTO THE GREAT LAKES AREA...AND SOME
INTENSIFICATION OF THIS ACTIVITY IS POSSIBLE WITH DAMAGING WIND THE
MAIN THREAT. IF SUFFICIENT DESTABILIZATION OCCURS...OTHER
STRONG-SEVERE STORMS MAY DEVELOP OVER CNTRL/SRN MN ALONG SEWD
ADVANCING FRONT DURING THE AFTERNOON.