2013 GLOV Severe Weather Discussion

[TimChgo9]

SPC has a Day 5 and a Day 6 outlined, for now, in today's Day 4-8.  NE IL is forecast for storms, or chances of storms, from Friday-Sunday, per ABC 7, and WGN's Weather Center App, seems to think Sun-Tues, with showers on Friday., and Partly cloudy on Saturday. NWS LOT seems to think t-storm chances, Friday-Monday. 

[YHM Supercell]

EC mentions a slight risk of severe thunderstorms overnight into Wednesday Morning for Southwestern Ontario...I may be wrong...but I see next to zero potential for severe storms tonight in Southern Ontario because of a strong cap in place keeping any storms that do form elevated...any ideas why EC would issue a slight risk? 

980 
ACCN10 CWTO 142020
FORECAST OF THUNDERSTORM POTENTIAL FOR THE PROVINCE OF ONTARIO
ISSUED BY ENVIRONMENT CANADA AT 4:00 PM EDT TUESDAY 14 MAY 2013.
THE NEXT STATEMENT WILL BE ISSUED AT 4.00 AM WEDNESDAY.
---------------------------------------------------------------------
FORECAST OF THUNDERSTORM POTENTIAL.

TONIGHT..ISOLATED NON-SEVERE THUNDERSTORMS OVER NORTHWESTERN ONTARIO
EARLY THIS EVENING.  ISOLATED NON-SEVERE THUNDERSTORMS OVER
NORTHEASTERN ONTARIO BEGINNING OVER THE SUPERIOR EAST REGION LATE
THIS EVENING THEN SPREADING EASTWARD OVERNIGHT. ISOLATED
THUNDERSTORMS LIKELY OVER SOUTHWESTERN ONTARIO AHEAD OF A WARM FRONT
OVERNIGHT.  THERE IS A SLIGHT RISK THAT SOME OF THESE THUNDERSTORMS
COULD BE SEVERE WITH LARGE HAIL AND TORRENTIAL DOWNPOURS BEING THE
MAIN THREATS. DAMAGING WINDS ARE A LESSER THREAT.

WEDNESDAY..THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WITH LARGE
HAIL AND TORRENTIAL DOWNPOURS MAINLY IN THE MORNING OVER
SOUTHWESTERN ONTARIO SOUTHWEST OF A LINE FROM SOUTHERN GEORGIAN BAY
TO WESTERN LAKE ONTARIO AS A WARM FRONT MOVES THROUGH. DAMAGING WINDS
ARE ALSO POSSIBLE. ACROSS SOUTH-CENTRAL, EASTERN AND NORTHEASTERN
ONTARIO ISOLATED NON-SEVERE THUNDERSTORMS WITH DOWNPOURS AND SMALL
HAIL ARE POSSIBLE NEAR AND AHEAD OF THE WARM FRONT.  THERE IS A
CHANCE OF AN ISOLATED NON-SEVERE THUNDERSTORM OVER NORTHWESTERN
ONTARIO NEAR THE MINNESOTA BORDER IN THE AFTERNOON AND EARLY EVENING.

THURSDAY..THERE ARE NO THUNDERSTORMS EXPECTED OVER ONTARIO.

---------------------------------------------------------------------
A THUNDERSTORM IS DEFINED AS SEVERE IF IT PRODUCES ONE OR MORE OF THE
FOLLOWING:

 - WIND GUSTS OF 90 KM/H OR GREATER.
 - HAIL OF 2 CENTIMETRES IN DIAMETER OR GREATER.
 - RAINFALL AMOUNTS OF 50 MILLIMETRES OR GREATER IN ONE HOUR OR LESS.
 - A TORNADO.

NOTE: THIS FORECAST IS ISSUED TWICE DAILY FROM MAY 1 TO SEPTEMBER 30.

END/OSPC

[harrisale]

 

EC mentions a slight risk of severe thunderstorms overnight into Wednesday Morning for Southwestern Ontario...I may be wrong...but I see next to zero potential for severe storms tonight in Southern Ontario...any ideas why EC would issue a slight risk? 

 

Not entirely sure. There is some potential for elevated convection and maybe some hail and wind gusts but ultimately low chance of anything severe. Strong cap and the models backing off instability has me skeptical of seeing anything decent.

 

Low level shear and helicity is pretty good which I guess EC is basing their forecast on? Also the NAM was showing 1500 j/kg CAPE this morning but have backed off since.

[wisconsinwx]

Almost all of the offices were discounting any convection forming with the front today, but the dewpoint overestimation was not as bad as they were thinking.  The models were still unrealistic with upper 60s dewpoints, but mid to upper 50s were realized.  Now hopefully the scant convection that has formed can maintain itself.

[wisconsinwx]

SPC has a Day 5 and a Day 6 outlined, for now, in today's Day 4-8.  NE IL is forecast for storms, or chances of storms, from Friday-Sunday, per ABC 7, and WGN's Weather Center App, seems to think Sun-Tues, with showers on Friday., and Partly cloudy on Saturday. NWS LOT seems to think t-storm chances, Friday-Monday. 

 

Given the snail's pace of the trough, we may keep pushing back the threat until we get to the following weekend.  Exaggerating, but maybe not by much.

[YHM Supercell]

Not entirely sure. There is some potential for elevated convection and maybe some hail and wind gusts but ultimately low chance of anything severe. Strong cap and the models backing off instability has me skeptical of seeing anything decent.

 

Low level shear and helicity is pretty good which I guess EC is basing their forecast on? Also the NAM was showing 1500 j/kg CAPE this morning but have backed off since.

Models were showing good instability for Wednesday Morning along the warm front as well as very favourable shear profiles. I was thinking some sort of S / SE moving MCS across SW/SC Ontario during the morning hours Wednesday but models really backed off instability and now have a pretty good cap in place...hopefully we can get a few rumbles though. 

[Stebo]

Business could be picking up for the region

 

DAY 4-8 CONVECTIVE OUTLOOK     

NWS STORM PREDICTION CENTER NORMAN OK   

0400 AM CDT WED MAY 15 2013       

VALID 181200Z - 231200Z       

 

...DISCUSSION...    A SEVERAL DAY EPISODE OF FAIRLY SUBSTANTIAL SEVERE WEATHER APPEARS    LIKELY ACROSS THE CENTRAL U.S. BEGINNING DAY 4 /SAT. 5-18/...AND    LIKELY CONTINUING THROUGH AT LEAST DAY 6 /MON. 5-20/.       

 

MEDIUM-RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH MUCH OF THE    PERIOD...AS AN UPPER TROUGH CROSSING THE ROCKIES AT THE START OF THE    PERIOD BEGINS AFFECTING THE PLAINS DAY 4.  THE TROUGH IS THEN PROGGED TO ENTER THE PLAINS DAY 5...AND THEN EVOLVE INTO A CLOSED    LOW DAY 6 AS A SECONDARY SPEED MAX ROTATES OUT OF THE ROCKIES AND    INTO THE PLAINS.      

 

AS THE TROUGH EVOLVES...A STRENGTHENING SURFACE SYSTEM IS LIKEWISE    EXPECTED TO MOVE ACROSS THE CENTRAL CONUS...LIKELY FOCUSING DAILY    DEVELOPMENT OF WIDESPREAD STORMS.  WHILE CAPPING WILL LIKELY BE AN    ISSUE -- LIMITING COVERAGE OF CONVECTION ALONG SRN REACHES OF THIS    DEVELOPING SYSTEM...EXPECT THAT STRONG LARGE-SCALE ASCENT WILL    PERMIT RELATIVELY WIDESPREAD CONVECTION OVER CENTRAL PORTIONS OF THE    COUNTRY FOR SEVERAL DAYS IN A ROW.       

 

THE GREATEST THREAT DAY 4 WILL LIKELY RESIDE FROM THE DAKOTAS SWD    INTO NRN KS...AS VERY STEEP LAPSE RATES CONTRIBUTE TO STRONG    DESTABILIZATION AND THE ERN FRINGE OF STRONGER FLOW ALOFT BEGINS TO    OVERSPREAD THE REGION.  LARGE HAIL AND DAMAGING WINDS WILL LIKELY BE    THE MAIN THREATS DAY 4.       

 

DAY 5...STRONG DESTABILIZATION IS AGAIN FORECAST WHICH -- COMBINED    WITH FAVORABLE SHEAR SPREADING FARTHER E...SUGGESTS THAT THREAT FOR    LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES SHOULD EXTEND    FROM THE MID MO VALLEY REGION SWD INTO KS/MO/OK AND VICINITY.       

 

ATTM...IT APPEARS THAT DAY 6 MAY BE THE DAY OF HIGHEST TORNADO    POTENTIAL...AS A REINFORCING MID-LEVEL SPEED MAX SHIFTS INTO THE    CENTRAL PART OF THE COUNTRY.  THE MAIN AXIS OF SEVERE WEATHER    APPEARS LIKELY TO EXTEND FROM THE IA/IL AREA SWWD ACROSS MO INTO    PARTS OF KS/OK/AR DURING THE AFTERNOON AND EVENING HOURS.       

 

THREAT MAY CONTINUE DAY 7...A BIT FARTHER E THAN DAY 6...BUT MORE    UNCERTAINTY AND HINTS OF SOMEWHAT DECREASED SEVERE POTENTIAL ARE    EVIDENT ATTM.  THUS...NO OUTLOOK AREAS WILL BE ISSUED BEYOND DAY 6    ATTM.

[A-L-E-K]

zzz

[Indystorm]

zzz

This year I'll believe svr wx occurs when I see it, but it does look as hopeful prognostically as it has yet this year.  Will wait and see what happens this weekend in the Plains and then on east at the first of the week.

[B-Rent]

I wouldn't mind a bit faster timing, going to be in sw mo for a graduation this weekend. Would make the trip home more enjoyable.

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[Hoosier]

This year I'll believe svr wx occurs when I see it, but it does look as hopeful prognostically as it has yet this year. Will wait and see what happens this weekend in the Plains and then on east at the first of the week.

I agree...looks like one of the better severe potentials thus far this season (I guess that's not saying much).

[Stebo]

Day 4 and 5 have grown in size for the region.

 

 

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0349 AM CDT THU MAY 16 2013

VALID 191200Z - 241200Z

...DISCUSSION...
MEDIUM-RANGE MODELS REMAIN IN BROAD/GENERAL AGREEMENT THAT
SUBSTANTIAL SEVERE WEATHER POTENTIAL EXISTS DAYS 4-5 /SUN. 5-19 AND
MON. 5-20/ AND POSSIBLY INTO DAY 6. HOWEVER...RATHER PRONOUNCED
DIFFERENCES IN TIMING/LOCATION OF SHORT-WAVE FEATURES CASTS
SUBSTANTIAL UNCERTAINTY REGARDING DETAILS OF THE UPCOMING SCENARIO.

IN GENERAL...THE TROUGH SHIFTING INTO THE PLAINS AT THE START OF THE
PERIOD IS FORECAST TO PROGRESS EWD IN A SOMEWHAT PIECEMEAL FASHION.
THE INITIAL/ENERGETIC SHORT-WAVE FEATURE SHOULD AFFECT THE CENTRAL
PLAINS SUNDAY...WITH RELATIVELY WIDESPREAD STORM DEVELOPMENT LIKELY
TO OCCUR ALONG A ROUGHLY N-S SURFACE BOUNDARY OVER THE CENTRAL
PLAINS REGION AS THE AIRMASS BECOMES MODERATELY TO STRONGLY UNSTABLE
DURING THE AFTERNOON. WITH 40 TO 50 KT SWLY MID-LEVEL FLOW ATOP
STRONG LOW-LEVEL SLYS...DEGREE OF SHEAR WILL COMBINE WITH THE VERY
FAVORABLE BUOYANCY TO ALLOW STORMS TO QUICKLY BECOME
SEVERE/SUPERCELLULAR...WITH VERY LARGE HAIL AND DAMAGING WINDS
EXPECTED ALONG WITH ISOLATED TORNADOES. SEVERE THREAT SHOULD
CONTINUE WELL INTO THE EVENING HOURS...THOUGH LIKELY DIMINISHING
SOMEWHAT OVERNIGHT.

MONDAY...WITH AN UPPER LOW FORECAST TO HAVE EVOLVED OVER THE NRN
PLAINS...A SECOND SHORTER-WAVELENGTH TROUGH IS PROGGED TO ROTATE
SEWD OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS REGION.
AGAIN...TIMING AND LOCATION OF THIS FEATURE DIFFERS AMONGST THE
VARIOUS MODELS...AND CONVECTION FROM SUNDAY WILL LIKELY HAVE
INFLUENCED THE SURFACE PATTERN SUBSTANTIALLY -- BOTH OF THESE
FACTORS YIELDING UNCERTAINTY WITH REGARDS TO THE SEVERE WEATHER
FORECAST. STILL...MODERATE TO STRONG INSTABILITY AND EMERGENCE OF
THIS SECOND/STRONGER SWLY MID-LEVEL JET STREAK SUGGESTS THREAT FOR
VERY LARGE HAIL...DAMAGING WINDS...AND TORNADOES AS AFTERNOON STORMS
ERUPT ACROSS THE MID MS/LOWER MO VALLEYS AND INTO PARTS OF KS/OK/N
TX AND POSSIBLY NWRN AR.

MODEL DIFFERENCES CONTINUE TO INCREASE INTO DAY 6 /TUESDAY/...WHICH
-- COMBINED WITH THE TWO PRIOR DAYS OF WHAT WILL LIKELY HAVE BEEN
WIDESPREAD CENTRAL U.S. CONVECTION/SEVERE WEATHER -- CASTS ENOUGH
UNCERTAINTY INTO THE FORECAST SUCH THAT NO AREAL DELINEATION OF
THREAT WILL BE INCLUDED ATTM BEYOND DAY 5. STILL...TUESDAY SEVERE
POTENTIAL WILL REQUIRE RE-EXAMINATION IN LATER OUTLOOKS AS AMPLE
SHEAR AND INSTABILITY FOR CONTINUED SEVERE POTENTIAL WILL LIKELY
EXIST.

 

[Thundersnow12]

Scored 3 tornadoes yesterday near Weatherford, TX. 

 

Might be a IA/IL day on Monday. 

[Stebo]

Scored 3 tornadoes yesterday near Weatherford, TX.

Might be a IA/IL day on Monday.

I agree, Monday is looking real good in the Northern half of the risk area.

[RCNYILWX]

Scored 3 tornadoes yesterday near Weatherford, TX. 

 

Might be a IA/IL day on Monday. 

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Was just gonna ask how the 18z gfs looked for IL, haven't had a chance to check it out yet. The 12z run looked good, pretty ominous forecast soundings.

[cyclone77]

I agree, Monday is looking real good in the Northern half of the risk area.

 

Tue might not be too bad either if the new Euro is right. 

[Stebo]

Tue might not be too bad either if the new Euro is right. 

 

Yeah the GFS isn't all bad either for GLOV.

[andyhb]

DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0228 AM CDT FRI MAY 17 2013
   
   VALID 191200Z - 201200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF GREAT
   PLAINS...UPPER MS VALLEY AND MID-MO VALLEY...
   
   ...SRN AND CNTRL PLAINS...
   AN UPPER-LEVEL LOW IS FORECAST TO DEVELOP ACROSS THE NRN PLAINS
   SUNDAY AS A NEGATIVELY-TILTED UPPER-LEVEL TROUGH MOVES EWD INTO THE
   SRN AND CNTRL PLAINS. AT THE SFC...A COLD FRONT IS FORECAST TO MOVE
   SEWD INTO THE SRN AND CNTRL PLAINS WITH DEWPOINTS AHEAD OF THE FRONT
   IN THE MID TO UPPER 60S F. THIS SHOULD RESULT IN MODERATE TO STRONG
   DESTABILIZATION BY LATE SUNDAY AFTERNOON FROM ERN KS SSWWD INTO
   ECNTRL OK. IN SPITE OF THE INSTABILITY...A STRONG CAPPING INVERSION
   SHOULD HOLD BACK CONVECTIVE INITIATION UNTIL LATE AFTERNOON. MODEL
   FORECASTS SUGGEST STORMS WILL INITIATE ALONG THE FRONT BY 00Z/MON
   WITH AN MCS ORGANIZING AND MOVING ESEWD ACROSS THE REGION. STRONG
   INSTABILITY COMBINED WITH IMPRESSIVE DEEP LAYER SHEAR PROFILES WILL
   CREATE CONDITIONS FAVORABLE FOR SEVERE THUNDERSTORMS. THERE EXISTS
   THE POSSIBILITY FOR WIDESPREAD SEVERE WEATHER INCLUDING A
   SIGNIFICANT SEVERE WEATHER EVENT.
   
   FORECAST SOUNDINGS AT 00Z/MON FROM KANSAS CITY SSWWD TO TULSA AND
   OKLAHOMA CITY SHOW MLCAPE VALUES OF 2500 TO 3500 J/KG WITH 0-6 KM
   SHEAR IN THE 45 TO 55 KT RANGE. A MID-LEVEL JET IS FORECAST TO MOVE
   THROUGH THE BASE OF THE UPPER-LEVEL TROUGH HELPING TO INCREASE DEEP
   LAYER SHEAR PROFILES AS THE EVENT UNFOLDS. THIS ALONG WITH STEEP
   MID-LEVEL LAPSE RATES SHOULD BE IDEAL FOR INTENSE SUPERCELL
   DEVELOPMENT. LARGE HAIL INCLUDING HAILSTONES OF GREATER THAN 2
   INCHES IN DIAMETER WILL BE POSSIBLE WITH THE MORE DOMINANT
   SUPERCELLS. IN ADDITION...A LOW-LEVEL JET IS FORECAST TO INTENSIFY
   EARLY SUNDAY EVENING WHICH SHOULD CREATE LOW-LEVEL SHEAR PROFILES
   FAVORABLE FOR TORNADOES. A FEW STRONG TORNADOES MAY ALSO OCCUR
   ESPECIALLY IF SUPERCELLS CAN REMAIN DISCRETE EARLY SUNDAY EVENING. A
   WIND DAMAGE THREAT MAY ALSO DEVELOP AND COULD BECOME ENHANCED IF A
   LINEAR MCS ORGANIZES.
   
   ...NRN PLAINS/UPPER MS VALLEY/MID-MO VALLEY...
   AN UPPER-LEVEL LOW IS FORECAST TO DEVELOP ACROSS THE NRN PLAINS ON
   SUNDAY AS SOUTH TO SOUTHWEST FLOW REMAINS IN PLACE ACROSS THE MID-MO
   VALLEY AND UPPER MS VALLEY. AT THE SFC...A LOW IS FORECAST TO MOVE
   SLOWLY ACROSS THE NRN PLAINS WITH A TROUGH EXTENDING SWD INTO THE
   MID-MO VALLEY. THE SFC TROUGH SHOULD BE THE FOCUS FOR CONVECTIVE
   DEVELOPMENT SUNDAY AFTERNOON. THE MODELS SUGGEST SEVERAL
   THUNDERSTORM CLUSTERS OR AN MCS WILL DEVELOP AND MOVE NEWD ACROSS
   THE REGION. A MODERATELY UNSTABLE AIRMASS IS FORECAST ALONG WITH
   STRONG DEEP LAYER SHEAR PROFILES SUGGESTING THAT WIDESPREAD SEVERE
   THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE SUNDAY AFTERNOON AND
   EVENING.
   
   FORECAST SOUNDINGS AT OMAHA AND DES MOINES AT 21Z/SUN SHOW MLCAPE
   VALUES IN THE 2000 TO 3000 J/KG RANGE WITH 40 TO 50 KT OF DEEP LAYER
   SHEAR. THIS COMBINED WITH STEEP LAPSE RATES SHOULD SUPPORT
   SUPERCELLS WITH LARGE HAIL. HAILSTONES OF GREATER THAN 2 INCHES WILL
   BE POSSIBLE IN THE MID-MO VALLEY WHERE THE STRONGEST INSTABILITY IS
   FORECAST. A FEW TORNADOES MAY ALSO OCCUR WITH THE MORE DOMINANT
   SUPERCELLS. THE SEVERE THREAT SHOULD BE MORE ISOLATED ACROSS ERN
   PARTS OF THE NRN PLAINS AND IN THE UPPER MS VALLEY WHERE INSTABILITY
   IS FORECAST TO BE WEAKER THAN IN AREAS TO THE SOUTH.
   
   ..BROYLES.. 05/17/2013

[IWXwx]

Think severe season is slow for Northern IN? These factoids bear it out:

 

Severe t-storm warnings issued by IWX in 2013 - 11

 

Average # by 5/15 (2005-2012) - 30.4

 

Most since 2005 - 53 (2006)

 

The winter around here was pretty vanilla (except for the March snowstorm) and the spring so far has been worse. I am really rooting for some action next week.

[A-L-E-K]

not liking our prospects

[Indystorm]

I'm still hopeful that if models continue to show what they are currently showing and shift that into our region come Mon/Tues we might see some significant action.   I do believe events in nature swing like a pendulum and the shift from svr storm drought to greater action may be happening.  Those recent 16 tornadoes in TX with the EF 4 in Granbury surprised me given the slight risk which was issued there.

[huronicane]

00z models looked more favorable last night, 06z GFS looked a little less, but still more enthused than the 12z NAM.  Got my fingers crossed something happens, though...I have been needing an excuse to take a day off of work.

[Hoosier]

http://www.americanwx.com/bb/index.php/topic/40268-may-19-21-severe-weather-threat

[Hoosier]

Business is about to pick up as we get toward the middle of next week and beyond. Models are still showing what could be a pretty significant multi-day severe weather outbreak. At this point I think the favored area for the best/most frequent threats is the central/upper Midwest. The farther east/south you are, the longer it will take, but everyone should have a shot eventually.

[Hoosier]

Looks like severe potential will pick up starting this weekend. GFS actually has some pretty impressive parameters especially as we get toward the early part of next week.

[Thundersnow12]

Looks like severe potential will pick up starting this weekend. GFS actually has some pretty impressive parameters especially as we get toward the early part of next week.

 

Sun/Mon look fun around here or just southwest of here on the southern fringe of the better mid-level WNW flow with lots of juice. GFS progging mid 70 dews on Monday. 

[Chicago Storm]

Ring of fire type pattern starting early next week.

[A-L-E-K]

Ring of fire type pattern starting early next week.

 

 

best pattern

[Stebo]

Looks like severe potential will pick up starting this weekend. GFS actually has some pretty impressive parameters especially as we get toward the early part of next week.

Yeah I am really impressed with Sunday, if we can get the instability back up this way it could really be a big day.

 

 

Ring of fire type pattern starting early next week.

best pattern

I love the Ring of Fire, daily MCSs are always fun to track.

[Thundersnow12]

Yeah, how can you not love these patterns. MCS after MCS running ESE along the front.