Friday Severe Weather Threat
SPC now has all WNY at Slight Risk for Severe Tstorms on Friday. Conditions will become more favorable for supercells, but low level wind shear could contribute to a few brief tornadoes. However, straightline winds look to be the principle threat, not tornadoes.
posted by Don Paul at
2:52 PM
31 Comments:
Any chance lake erie weakens the storms dramaticcaly as it usually does or will the storms be elevated your thoughts?
dramatically*
Boundary layer winds will be ESE, so Lk Erie will have little effect, in addition to some of the tstorms being elevated convection.
Hey Don, thanks for the heads up. I haven't checked the convective outlooks yet today over at SPC. Any clue to the timing here? I'll have a classroom full of kids and it might be helpful to know.
str
No good clue to the timing, since this threat will be tied to a lengthier period of a strong low level and higher level jetstream, rather than a cold frontal passage. As a warm front gets closer to WNY in the predawn hours, there may be a few elevated tstorms. The threat of severe storms may be somewhat higher south of that front tomorrow, in the srn tier and nrn PA, but svr storms can also form in the vicinity of and just north of a warm front. The primary threat, if supercells pass over our region, will be damaging straightline winds. However, there may be enough low level directional wind shear (winds that veer westerly with increased altitude) and speed shear to spin up a few tornadoes in Ohio, PA, and a lesser risk--but still a risk--in WNY.
By the way, I thoroughly enjoyed myself today at the "Luncheon with Don Paul" at Buffalo State. Dr. Stephen Vermette, of the Geography Dept (with a thorough background in climatology) invited me to chat with Buff State students, some minoring in meteorology (the 4 year met degree isn't offered there, but the
geography/meteorology program is expanding), along with some faculty members and some members of the WNY Local Chapter of the AMS. Since everyone kept their lunch down, I guess it went fairly well. A friendly, inquisitive group--very stimulating.
Now, back to the svr weather discussion....
eyes on the sky tomorrow...guess I'd better put the gardening tools away. Keep a close eye on your cats...they can sense these storms really well.
I'll be checking in on the doppler and will report anything thats happening tomorrow. I hope others do as well...we can keep a good track of the cells as they pass over...if they do, that is...
Its been a long break of uneventful weather... looks as if that may soon come to an end. I like spring T-Storms, however, I also know how much damage they can do! Keep an eye on the sky tomorrow...
THE POTENTIAL FOR
THUNDERSTORMS AND SEVERE WEATHER...IT SHOULD BE EMPHASIZED THAT IF
CONVECTION DOES ACTUALLY BREAK OUT...THE BULK OF IT WILL BE
ELEVATED. THE VARIOUS GUIDANCE PACKAGES ARE STILL OUT OF SYNC IN
TERMS OF HOW FAR NORTH THE WARM FRONTAL BOUNDARY WILL LIFT...BUT
ANY CONVECTION THAT DOES BREAK OUT IN THE VICINITY OF THIS FRONTAL
BOUNDARY WILL CARRY THE POTENTIAL TO PRODUCE SEVERE WEATHER.
HELICITY VALUES IN EXCESS OF 500 M2/S2 WILL BE FOUND WITHIN 10-20
MILES EITHER SIDE OF THIS BOUNDARY...WITH LOW LCL`S AND FREEZING
LEVELS AT OR BELOW 10K FT. STRONG JET DYNAMICS WILL BE IN PLACE AS
WELL...WHICH SHOULD FAVOR STRAIGHT LINE WIND AND OR HAIL CONCERNS
FROM THE STRONGER STORMS. INTERESTINGLY...THE SFC MAP FRIDAY
MORNING WILL NOT BE TOO DISSIMILAR FROM THE ONE FROM APR 28 2002
WHEN A WELL DEFINED WARM FRONT STRETCHED EAST ACROSS THE SRN TIER
FROM A TRIPLE POINT/SFC LOW IN THE VICINITY OF LK ERIE.
ANY STORMS THAT FORM NEAR THE WARM FRONTAL BOUNDARY WILL HAVE TO
BE VERY CLOSELY WATCHED...AS HISTORY OVER OUR REGION HAS SHOWN
THIS TO BE A FAVORABLE PATTERN FOR ROTATING STORMS AND SHORT LIVED
TORNADOES.
Yes, I got a call from this NWS met earlier this evening who noted I'd mentioned at 6 a remote risk of a few tornadoes, and he filled me in on this similar setup from 6 years ago.
It's still very difficult to place this warm front tomorrow, with the NAM keeping it well south of the metro area, and the GFS bringing it closer to the metro area. The helicity values (feel free to Google "helicity"--it's too late for me to launch into an explanation) do tend to be higher in closer proximity to a warm front in this type of synoptic setup.
My own forecast is to keep the warm front far enough south of the metro area so that these helicity values would likely be found closer to the PA line. That would also keep Buffalo temps in the low 50s, while our PA viewers have highs in the mid 60s. (75 in Charleston WVA at 11pm and 67 in Pittsburgh). The convection north of the warm front will tend to be elevated in nature (not surface-based, and therefore not seriously impacted by Lk Erie), while the vigorous storms south of the warm front would tend to be more surface based, and more dependent on surface heating to maximize instability.
I'm wondering what the difference is between thunderstorms that form due to daytime heating, and thunderstorms that occur at night where I would think the atmosphere would be more stable without the sun's influence. What makes the atmosphere "bubbly", as Don says, at night?
Quite a dramatic difference in temperature forecast today.
In the warm sector, in southwestern Ontario, Windsor-Sarnia high of 21 C/70 F, even 16 C/61 F in London.
In the cooler pocket, Toronto has 5 C/40F while just north of the big smoke, we've got a freezing rain warning with plain rain mid morning and same high.
All locations run the risk of t-storms, but Envir. Can. says there is a SLIGHT risk of severe storms with large hail/damaging winds as the warm front brings a brief vist of unstable air to SW. Ont.
Should be an interesting weather day in Southern Ont. and WNY.
SPC has WNY out of the Slight Risk area.
Hey Don,
I was just going to send out a blog asking what happened to the slight risk of severe t-storms that you made mention of last evening. I just replayed Mike's weather and there was nary a word about a risk of strong storms? Had the risk been lifted by then?
As I said last night, I was going with keeping the warm front fairly well suppressed south of Buffalo.
We have elevated instability, but it's currently seen insufficient to produce severe storms late today. Surface-based instability is nearly nil, but as the warm front gets closest late today, parameters for convection will improve late afternoon (after some sunny breaks) and early evening, with the best chance for tstorms closer to PA. While the Lk Ontario shoreline of WNY will stay in the low/mid 40s, places like Bradford can expect to approach 70 later today.
While SPC has taken us out of the Slt Risk in their morning outlook, I still can't rule out a few Isolated intense or Svr storms near PA near the end of the day. We will have improved parameters at that time, and still a fair amount of helicity in the lower levels at that time.
To learn more about convective parameters, Google SPC Hourly Mesoscale Analysis, click on one of the rectangles, and you can go over analysed parameters, observations, radar, satellite, and indices. Each has a tutorial. But a warning--this site was designed for meteorologists, and some tutorials involve very complex mathematical and physical concepts.
The warm front is, after all, making some decent progress northward early this afternoon. While it's 47 at NF, it's 65 at Dunkirk. This warm front will increase elevated instability north of the front, and surface based instability near and south of the front late today and early tonight. No time to go into all the particulars, but I believe the risk of at least Isolated strong-to-Severe Tstorms will increase toward evening and into the evening--especially south of Buffalo.
Don,
Tornado watch issued by Envir Can. for Windsor-Sarnia and Chatham area. Strong storms expected mid-afternoon. A balmy 21 Cel/70F in Windsor. Beats our 1C/35 F, but at least we don't have the tornado threat.
We get lake effect rain here as well as snow don't we? What sets that up if so? Sometimes it seems when the rest of the state and Ohio has draught we get by with just a bit more rain that saves out crops. Is there any chance that is from the Lakes, Don Paul?
Lake rains are caused by the same mechanism as lake snows. It's just not cold enough at the surface for snow--typically happens most in Sept-Oct.
Good sfc heating developing south of the advancing warm front--Dunkirk into low 70s on a downslope breeze. Surface based instability will definitely increase, with the best chance for strong-to-svr storms probably near Chau Co by early evening. Still a low risk, but a real one--SPC may have yanked WNY out of the Slt Risk area prematurely, though early today it looked like the warm front would stay further south.
OK Don that makes sense. I guess I was not thinking that through. The fall rains don't make that much difference to the crops I don't think except in that we have a higher total rainfall than some areas and may have a better ground water situation.
How's it look for the home opener tonight? Do you think they will get the whole game & fireworks in? Also how cold do you think it will be @ the park?
Looks like rain and thunderstorms near cleveland, some of that is headed our way, by the way it is now 72 degrees here in southern erie county, prbably tying our warmest day, also i saw the airport just hit 67.
Amazing it is 42 in Albion and here in Stafford it is 68.
38 at Barker and 69 at both Springville and Gowanda as of 5:20.
http://www.wunderground.com/US/Region/US/2xVisSatellite.html
This CONUS visible satellite URL shows the size of the storm and its classic formation. notice the sqall line of really high cloud tops entering NE Ohio as of this time stamp.
Will the cooler temps closer to Lake Ontario help to diminish the chance of t-storms in this area? It would seem so, but who am I to say? I know Don said at 5 that best chance would be south for severe t-storms. Does the cooler air reduce the....ummm...is it convection that gets them going?
excuse me, that was NW Ohio.
Lake Erie is taking a toll on some tstorms which are, essentially, falling apart near Chau Co. While some Tshwrs are still likely this evening, the threat of Svr is becoming Remote.
Another stronger line of Tstorms now extending across Lk Erie through Cleveland and its ern suburbs is racing NE--after that squally line passes, things will settle down. Still in the mid/upper 30s over nrn Niag & Orl Counties as of 9:50, while Buffalo area is in the low 60s.
Our lightning detection display system shows rapid weakening of storms approaching from the SW, though they will still produce some downpours between 11:30 & 1 from SW to NE.
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