Tornado Potential for August 19, 2005

[wxmann_91]

Moderators, if you want to move or delete this topic, then well, feel free to do so.

Anyway, today's situation looks particularly volatile, in fact, similar to yesterday. SPC paints a MOD risk and a 15% chance of tornadoes. Storm-relative helicity (SRH), like yesterday, will be quite high, and a dry slot is already moving into the area. The best dynamics will be to the north, but a warm front and the ULL will provide sufficient turn to trigger some tornadoes south of the border, to the east of Cleveland. Any outflow boundaries will enhance SRH and increase the chance of a strong tornado. Of course, once the storms cross the warm front in central PA, they will quickly die out, daytime heating and the mountains will be hindering development later this evening also. But the key to today's tornado potential will be if storms remain discrete and supercellular, like yesterday, or will congeal into a squall line quickly, thus limiting the tornadoes.

But this is not the only place where tornadoes are possible. IA has a chance for tornadoes, though low level flow is quite meager, but other parameters, such as LCL's, and good SRH. Speed shear is more than enough for supercells, >45 kt. Large hail appears to be the main danger here, but tornadoes cannot be ruled out, and SPC is considering a moderate risk over this area.

The latest RUC shows a jet streak moving into IA and another moving into the lower Great Lakes, and some good SRH in western NY/western PA and in southeastern SD, around where initiation should begin.

http://www.rap.ucar.edu/weather/model/ruc09hr_500_wnd.gif
http://www.rap.ucar.edu/weather/model/ruc09hr_sfc_sreh.gif

Latest NAM shows great amounts of SRH in NY and PA, with lesser amounts over IA and eastern NE.

http://www.rap.ucar.edu/weather/model/eta12hr_sfc_sreh.gif

Public Severe Weather Outlook is out, be careful for those living in the affected areas.

[wxmann_91]

Newest SWODY1 also shows MDT risk over in Iowa/southeast NE/northeast KS/northwest MO as well as western PA/western NY/eastern OH.

Latest PSWO:

ZCZC SPCPWOSPC ALL
WOUS40 KWNS 191659
IAZ000-KSZ000-MOZ000-NEZ000-NYZ000-OHZ000-PAZ000-WVZ000-200100-

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT FRI AUG 19 2005

VALID 191659Z - 200100Z

...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER GREAT LAKES
AND OHIO VALLEY REGION TODAY...AND PORTIONS OF THE EAST-CENTRAL
PLAINS TODAY AND TONIGHT.

THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
DEVELOPMENT OF TORNADOES...LARGE HAIL AND DAMAGING WINDS OVER PARTS
OF THE LOWER GREAT LAKES AND OHIO VALLEY REGION TODAY...AND PORTIONS
OF THE EAST-CENTRAL PLAINS LATER TODAY AND TONIGHT.

THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE

MUCH OF IOWA
NORTHEASTERN KANSAS
NORTHERN MISSOURI
EASTERN NEBRASKA
WESTERN UPSTATE NEW YORK
EASTERN OHIO
WESTERN AND CENTRAL PENNSYLVANIA
NORTHERN PANHANDLE OF WEST VIRGINIA

SURROUNDING THE TWO MODERATE RISK AREAS...THERE IS A SLIGHT RISK OF
SEVERE THUNDERSTORMS FROM CENTRAL NEW YORK AND THE NORTH-CENTRAL
APPALACHIANS WESTWARD TO CENTRAL PORTIONS OF NEBRASKA AND KANSAS.

...EASTERN AREA...
TORNADOES...DAMAGING THUNDERSTORM GUSTS AND LARGE HAIL ALL ARE
POSSIBLE. A VERY MOIST AND UNSTABLE AIR MASS ACROSS THE OHIO VALLEY
IS EXPECTED TO SPREAD NORTHEASTWARD TODAY AHEAD OF AN UPPER LEVEL
TROUGH MOVING ACROSS THE GREAT LAKES AND SOUTHERN ONTARIO. AS THIS
HAPPENS...MODEST MID-UPPER LEVEL WINDS WILL SPREAD OVER MUCH OF THE
SAME REGION...FAVORING ORGANIZED SEVERE THUNDERSTORMS INCLUDING A
FEW SUPERCELLS. ACTIVITY SHOULD WEAKEN THIS EVENING AFTER PASSING
THE APPALACHIAN CREST...AS AIR MASS BECOMES MORE STABLE.

...WESTERN AREA...
WIDESPREAD AND POTENTIALLY DAMAGING THUNDERSTORM WIND EVENT IS
POSSIBLE ALONG WITH LARGE HAIL. THUNDERSTORMS SHOULD DEVELOP AND
STRENGTHEN THROUGHOUT THE REST OF THE DAY OVER PARTS OF KANSAS AND
NEBRASKA. INCREASING INSTABILITY AND A BELT OF STRONGER WINDS IN
MIDDLE-UPPER LEVELS WILL SUPPORT CLUSTERS OF ORGANIZED SEVERE
THUNDERSTORMS...CONTINUING THROUGH THIS EVENING INTO TONIGHT OVER
IOWA AND PERHAPS NORTHERN MISSOURI.

THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE WEATHER
SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA WEATHER
RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS LATER TODAY.

..EDWARDS.. 08/19/2005

$$

[wxmann_91]

WOW it's GREAT to talk to yourself on a thread.

Anyway, already tornado reports and damage in the Toronto area (this info from Environment Canada):

City of Toronto
3:31 PM EDT Friday 19 August 2005

Tornado warning for
City of Toronto continued

Radar is detecting a line of severe rotating storms in the Toronto
area. There have been several reports of tornadoes and damage within
this line of storms. These storms are moving eastward at 70 km/h.

[ohiostorm]

Our nws has us in a moderate threat for severe weather this evening. Our dew points are in the lower 70's so the possibility is there. Nothing on radar for hundreds of miles except for a few small cells. Calm before the storm I guess?

Now your not talking to yourself.

[simplykristi]

The KC area is under a severe Thunderstorm Watch. Storms are off to my north and west.

Kristi

[wxmann_91]

Our nws has us in a moderate threat for severe weather this evening. Our dew points are in the lower 70's so the possibility is there. Nothing on radar for hundreds of miles except for a few small cells. Calm before the storm I guess?

Now your not talking to yourself.

LOL thanks.

The situation isn't looking as dangerous for Pennsylvania or Ohio anymore, the air is a bit more stable and the temperatures aloft are warming up, thus indicating that the cap is actually pretty stout in that area (this was indicated by the NWS Cleveland AFD this morning). But residents in southern Ontario and western NY should continue to monitor this situation.

[ohiostorm]

Tornado Watch now for portions of NY state.