September 2 - 3: Severe Weather Risk, Late-season thunderstorms for Ontario? Options

[an uncanny otter]

Summer may be dying down, and along it the frequency of severe weather outbreaks. However, as the heat and humidity builds back into Ontario by the weekend, along with it is the possibility of late-season thunderstorms.

It's a Day 4 risk map, so it's still quite far out, but the potential is certainly there for some strong thunderstorms to break out in southern Ontario.



ZCZC SPCSWOD48 ALL
ACUS48 KWNS 310916
SPC AC 310916

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0416 AM CDT WED AUG 31 2011

VALID 031200Z - 081200Z

...DISCUSSION...
RELATIVE RUN-TO-RUN CONSISTENCY AND GOOD AGREEMENT AMONGST THE
MODELS AND ENSEMBLES REVIEWED FOR THIS FORECAST SUGGEST SOMEWHAT
HIGHER-END SEVERE POTENTIAL MAY EVOLVE ACROSS THE MIDWEST/OH VALLEY
REGION ON D4/SATURDAY INTO D5/SUNDAY. THIS SHOULD OCCUR AS ANOTHER
STRONG SHORTWAVE TROUGH PROVIDES A REINFORCING SURGE OF COOLER AIR
ACROSS THE UPPER MIDWEST AND RESULTING LIFT ALONG THE ADVANCING COLD
FRONT ENCOUNTERS WARMING AND MOIST AIRMASS. THE AREA DEPICTED FOR D4
IS THE REGION WHERE ENSEMBLE OUTPUT SUGGESTS THE HIGHER PROBABILITY
OF CONVECTIVE QPF WILL COINCIDE WITH A MEAN MUCAPE AROUND 1000 J PER
KG. THIS WILL ALSO BE THE AREA LIKELY TO EXPERIENCE SOMEWHAT
STRONGER DEEP-LAYER FLOW ON THE EDGE OF THE STRONGER WLYS ALOFT.

THE TRAILING PORTION OF THE COLD FRONT...ESPECIALLY THAT SEGMENT
INTO THE HIGHER TERRAIN OF THE FRONT RANGE AND SRN HIGH PLAINS WILL
ALSO SERVE AS A FOCUS FOR SCATTERED TSTMS. HOWEVER...DEEP-LAYER FLOW
ACROSS THESE AREAS IS MORE MARGINAL TO SUPPORT A RISK AREA AT THIS
TIME.

BEYOND D4...A WIDE DISPARITY IN MODEL SCENARIOS BEGINS TO
EVOLVE...ESPECIALLY WITH EVOLUTION OF GULF OF MEXICO LOW PRESSURE.
GIVEN THE WIDE SPREAD IN THE FORECASTS...UNCERTAINTY IN SEVERE STORM
DEVELOPMENT AND COVERAGE IS HIGH. HOWEVER...LARGER SCALE PATTERN
DEPICTED IN THE 00Z NCEP MREF SOLUTIONS SUGGESTS THAT THE EVOLVING
PATTERN WILL GENERALLY ACT TO SUPPRESS SEVERE WEATHER ACTIVITY GOING
INTO NEXT WEEK.

..CARBIN.. 08/31/2011

This post has been edited by an uncanny otter: Sep 2 2011, 06:10 PM

[bwfan]

Latest 2 Day Outlook from NOAA. We might see some stormy weather - hopefully tomorrow will provide a better resolution on what will evolve!

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE U.P. OF MI SWWD ACROSS
SERN WI...

...SYNOPSIS...
STRONGER MID LEVEL CYCLONIC FLOW WILL BECOME WELL ESTABLISHED ACROSS
THE NCNTRL STATES AND SCNTRL CANADA THIS PERIOD WHICH WILL ACT TO
SUPPRESS/BREAKDOWN ERN FLANK OF PERSISTENT UPPER RIDGE FROM THE
MIDDLE MS VALLEY ACROSS THE MIDWEST. MEANWHILE...TROPICAL SYSTEM IN
THE GULF WILL CONTINUE TO EVOLVE WITH THE BULK OF MODEL GUIDANCE
SUGGESTING AN INCREASE IN LOW LEVEL FLOW/SHEAR ACROSS THE LA
COASTLINE.

AS A MODERATELY STRONG LEAD SHORTWAVE IMPULSE...NOW OVER THE
INTERIOR NW...LIFTS INTO ONTARIO...ASSOCIATED TRAILING COLD FRONT
WILL SETTLE ACROSS THE GREAT LAKES AND EXTEND FROM U.P. OF MI SWWD
INTO THE SRN HIGH PLAINS BY FRIDAY AFTERNOON. THE NEXT UPSTREAM
SHORTWAVE TROUGH WILL SPREAD HEIGHT FALLS ACROSS THE NRN PLAINS LATE
IN THE PERIOD WITH ANOTHER COLD FRONT MOVING ACROSS ERN MT AND ND
AFTER DARK.

...U.P. OF MI SWD ACROSS LAKE MI TO SERN WI...
MODEST LOW-LEVEL SWLY FLOW WILL TRANSPORT HIGHER DEWPOINTS NEWD FROM
THE CORN BELT ACROSS WI/MI AHEAD OF THE COLD FRONT. SMALL MCS MAY BE
ONGOING NEAR AND/OR BEHIND THE FRONT ACROSS IA EARLY IN THE PERIOD.
AS UPPER TROUGH LIFTS INTO CANADA...IT APPEARS SUFFICIENT LARGE
SCALE HEIGHT FALLS AND ASCENT WITHIN RIGHT ENTRANCE REGION OF UPPER
JET WILL ENHANCE FORCING ALONG THE FRONT MOVING ACROSS WI/LAKE MI
DURING THE AFTERNOON. INCREASING DEEP-LAYER WLY FLOW COUPLED WITH
MLCAPE AROUND 1000 J PER KG AHEAD OF THE FRONT SHOULD AID STORM
ORGANIZATION/INTENSITY WITH ONE OR TWO FAST-MOVING LINE SEGMENTS
BRINGING A HEIGHTENED POTENTIAL FOR DAMAGING WINDS DURING THE LATE
AFTERNOON.

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[ottawasnowstorm]

It could get interesting on tomorrow, saturday, but there are some "perhaps" unexpected severe thunderstorm warnings now just northwest of Toronto in regions such as York.

Ottawa also just had a brief light thunderstorm which Toronto also did. And there may be more judging by EC's radar.

Now, where are all you guys who track these storms with me, you guys are always here when storms like these hit! Not too much fun without ya all!

This post has been edited by ottawasnowstorm: Sep 2 2011, 05:16 PM

[an uncanny otter]

Tornado Warnings issued for northern Ontario:

Kirkland Lake - Englehart
6:56 PM EDT Friday 02 September 2011
Tornado warning for
Kirkland Lake - Englehart continued

Persons in or near this area should be on the lookout for adverse weather conditions and take necessary safety precautions. Watch for updated statements.

Please refer to the latest public forecasts for further details and continue to monitor the situation through your local radio and television stations or Weatheradio.

[ottawasnowstorm]

No watches or warning for southern and eastern ontario anymore but northern ontario is still in the tornado warning (Kirkland Lake). Though EC's radar shows the storms have moved out of Kirkand lake and are now mostly in Quebec. Could be an interesting day tomorrow in southern/eastern ontario and a perfect summer day for me, high heat and humidity first, then potential severe thunderstorms after. Life is good!

This post has been edited by ottawasnowstorm: Sep 2 2011, 06:39 PM

[EOsnowmom]

I think we might want to extend the title of this thread to include Sept 4. Sunday looks as promising as the other days.

[bwfan]

Severe thunderstorm watch for
Sarnia - Petrolia - Western Lambton County
Watford - Pinery Park - Eastern Lambton County
Windsor - Leamington - Essex County
Chatham-Kent - Rondeau Park issued

Severe thunderstorms possible this afternoon..

This is an alert to the potential development of severe thunderstorms with large hail, damaging winds or heavy rainfall..Monitor weather conditions and listen for updated bulletins.

A cold front is expected to sweep across Southwestern Ontario this afternoon. A very hot and humid airmass over these regions will provide sufficient energy for strong thunderstorms to develop this afternoon over Sarnia and Windsor regions. Some of these thunderstorms may become severe with large hail, damaging winds, and torrential downpours.

[HoBOonFiRE]

A decent looking cell about to hit somewhere between Kincardine and Goderich. No warnings as of yet.

This post has been edited by HoBOonFiRE: Sep 3 2011, 11:12 AM

[bwfan]

Strathroy - Komoka - Western Middlesex County
10:42 AM EDT Saturday 03 September 2011
Severe thunderstorm watch for
Strathroy - Komoka - Western Middlesex County issued


London - Parkhill - Eastern Middlesex County
10:42 AM EDT Saturday 03 September 2011
Severe thunderstorm watch for
London - Parkhill - Eastern Middlesex County issued

Severe thunderstorms possible this afternoon..

This is an alert to the potential development of severe thunderstorms with large hail, damaging winds or heavy rainfall..Monitor weather conditions and listen for updated bulletins.

A cold front is expected to sweep across Southwestern Ontario this afternoon. A very hot and humid airmass over these regions will provide sufficient energy for strong thunderstorms to develop this afternoon over the above regions. Some of these thunderstorms may become severe with large hail, damaging winds, and torrential downpours.

[ottawasnowstorm]

SEVERE THUNDERSTORM WARNING just issued for Toronto!

Looks like a decent downpour is just beginning judging by radar.

[ottawasnowstorm]

Although the severe thunderstorm warning remains for Toronto, the thunderstorm appears to be just east of the city now after rolling through from the west so it should be improving in the city. EC mentioned that wind gusts could be at 100 km/hr.

[bwfan]

NOAA has issued severe thunderstorm watches for all SE Michigan...could be an active night as they anticipate storms through 3AM.

This post has been edited by bwfan: Sep 3 2011, 03:38 PM

[an uncanny otter]

Michigan tornado warnings:

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
447 PM EDT SAT SEP 3 2011

THE NATIONAL WEATHER SERVICE IN DETROIT/PONTIAC HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHEASTERN SANILAC COUNTY IN SOUTHEAST MICHIGAN...

* UNTIL 515 PM EDT

* AT 446 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED 6 MILES SOUTHWEST OF LEXINGTON...AND MOVING EAST
AT 20 MPH.

* THIS DANGEROUS STORM WILL BE NEAR...
BIRCH BEACH AND LEXINGTON HEIGHTS AROUND 455 PM EDT.

THE WARNING INCLUDES AREAS SURROUNDING THESE LOCATIONS...
LEXINGTON... CROSWELL...

It's a really nasty-looking cell that's just moving out over Lake Huron now. Areas on the shorelines of the lake should watch out.

[an uncanny otter]

Kitchener got hit with some high winds and heavy rains with the cell that went through. Some injuries reported. My family was there today D:



This post has been edited by an uncanny otter: Sep 3 2011, 04:12 PM

[ottawasnowstorm]

SEVERE THUNDERSTORMS are all over the place in southern ontario currently, almost everywhere west and south/southwest of Toronto. The lightning detector at EC is showing several reds and multiple oranges. Toronto will probably get back in on the action at any time. Must be an amzing light show down there.

[Astronomer]

Lots of flashes and rumbles to my west - no direct action yet just west of London.

[EOsnowmom]

Tomorrow's (Sept 4) map updated:

I'm not too happy about this, but you severe weather lovers enjoy!



http://www.spc.noaa.gov/products/outlook/d...lk_1730_any.gif

[Astronomer]

More than 1 flash-per-second happening in my skies right now!

[TriC]

More than 1 flash-per-second happening in my skies right now!

Ya same here in west London... its like a strobe Light.

[Astronomer]

Ya same here in west London... its like a strobe Light.

No kidding! Not quite like the strobe from a couple of weeks ago, but pretty darned close.