Storm Threat: April 25-27.11

[benjaminblizzard]

EC is predicting tstorms for Toronto as well. Fingers crossed!

[benjaminblizzard]

From SPC's Day 2 Convective Outlook as of 0100 AM CDT today.

.

..LOWER GREAT LAKES REGION/OH AND TN VALLEYS...
THUNDERSTORMS ONGOING AT THE START OF THE PERIOD WILL CONTINUE
SHIFTING NEWD ACROSS THE TN/OH VALLEYS AND INTO THE LOWER GREAT
LAKES REGION. THIS WILL OCCUR AS STRONG SHORT-WAVE TROUGH SHIFTS
ACROSS THIS AREA FOCUSING LARGE-SCALE UVV ALONG A SURFACE COLD FRONT
EXTENDING SWWD ACROSS THE MID MS VALLEY INTO TX. WHILE AFTERNOON
HEATING MAY BE HINDERED BY WIDESPREAD PRECIPITATION/CLOUD
COVER...LOCAL AREAS OF GREATER DESTABILIZATION WILL SUPPORT
AFTERNOON INCREASE IN STORM COVERAGE AND INTENSITY -- AS FAR NE AS
PA AND NY NEAR THE SURFACE WARM FRONT.

WITH A STRONG SWLY FLOW FIELD ALOFT ACROSS THIS ENTIRE AREA
/LOW-LEVEL FLOW INCREASING FROM 50 TO 65 KT IN THE 850 TO 500 MB
LAYER/...SHEAR WILL SUPPORT ORGANIZED/ROTATING STORMS...ALONG WITH
LINEAR/BOWING SEGMENTS. ALONG WITH SOME THREAT FOR HAIL...DAMAGING
WINDS WILL BE LIKELY ALONG WITH THE POTENTIAL FOR ISOLATED
TORNADOES. THE THREAT SHOULD SPREAD EWD WITH TIME AS THE FRONT
SLOWLY ADVANCES...WITH SOME THREAT LIKELY LINGERING INTO THE
OVERNIGHT HOURS INTO NY/PA/WV.

[Smokin Joe]

I wish SPC would finish the portion of the risk area that is over Ontario.....that would be way more satisfying if they just finished the damn line lol! EC should throw some cash to SPC to finish the map over canada and provide a link from their website
if they really wanted canadians safe they should think outside the box if they don't want to spend to set up the infrastructure here then just pay some cash to get it done for us.

[DarkSky]

Day 1 risk looks nice :



But check out Day 2 !!!

[fitzcalvin]

SWS issued by EC (for all of southern and eastern Ontario) at 11:22 this morning. I agree that Wednesday looks like the day to watch, particularly for those of us in Eastern Ontario (the Ottawa Valley, in my case).

WOCN11 CWTO 251522
Special weather statement
Issued by Environment Canada at 11:22 AM EDT Monday 25 April 2011.

..Significant rainfall tonight and Tuesday..

---------------------------------------------------------------------
==discussion==
An intensifying low pressure system located over the southern plains
of the United States will track slowly toward the Great Lakes regions
tonight. Rain in advance of this system will continue to spread
northeast through Southwestern Ontario this afternoon and through
southcentral and Eastern Ontario tonight and Tuesday. The rain could
be heavy at times and accompanied by isolated thunderstorms as the
low pressure centre gets closer to the Great Lakes tonight.
Heavy rain is expected to taper off to a few showers early Tuesday
morning before another bout of heavy rain and a few thunderstorms,
associated with a cold front sweeps in Tuesday afternoon and evening.

In general, total rainfall amounts of 30 to 40 mm are expected during
this event. Embedded thunderstorms could give locally higher
amounts.

[Anspray]

So realistically a rain event for southern Ontario? That's my prediction.

[davefootball123]

I was just looking at the latest SREF SIG TOR. Looking pretty good. http://www.spc.noaa.gov/exper/sref/s...bined_sigtor__

[davefootball123]

Just thought i would post an update on the possible storms tomorrow and wednesday.
First off it looks just as good as it did earlier today. There does appear to be marginal instability and with type of system even 500-1000j/kg CAPE is more than sufficent. It is also early for Southern Ontario to have high CAPE values considering it is still april. There appears to be a large amount of shear. 0-6km bulk shear values of at least 50kts throughout all of southern ontario. I was looking at the SREF sig tor and it appears that with the helecity and the shear available there may be an isolated tornado possible however the best risk for tornadoes is deffenitley in the ohio valley/mid south states tomorrow. I was also taking a look at the latest soundings on the GFS model http://www.twisterdata.com/index.php...sounding.y=250
That sounding is for the Hamilton/Niagara area and it indicates surface temps in the 20's with dewpoints approaching or hitting 20 degrees. As you can see the air does cool off signifigantly as you approach mid levels in the atmosphere indicating some strong storms could produce some hail. That latest NAM also indicates that the storms will have a damaging wind threat as is always the case with linear systems. The possibility for storms on wednesday looks much the same as tuesday . The risk is basicly the same for both days. Damaging winds are a possibility as well as some hail and mabye just mabye an isolated tornado given the fact that some of the tornadoes in the past week have formed in some very marginal instability in northern/central ohio.

To round it off with the timing. The NAM,WRF and GEM all indicate that on Tuesday the possible squall line would come through between 4 and 8pm. I can not pin point the exact time beacuse the models are subject to changing through each run. The WRF and GEM are particularly impressive with this system bringing a well defined squall line through southwestern ontario and then through the golden horshoe as well as areas somewhat further north too

EDIT: Timing is looking a little more confident between each model. The GEM,WRF,and NAM all put the line through hamilton at around 22z or 6pm and on Wednesday the storms are a little bit more tricky to anticipate the timing however it looks to be after 7pm at least atm

[stormy kid]

so sweet if we get severe thunderstorms on Tues. afternoon getting the cam ready lol...

[SlideShowBob]

I can't wait...I've got the day off Tuesday. Could be an active few days. Best of luck everyone and stay safe!