Severe Weather Threat: Tuesday, October 26th

[Mr. Rainman]

The convective outlook for Tuesday. Much of the U.S. east of the Mississippi is facing some serious weather.


To give a simplified picture, the probability of severe weather impacting the area.


From Wikipedia: A moderate risk day indicates that more widespread and/or more dangerous severe weather is possible (sometimes with major hurricanes), with significant severe weather often more likely. Numerous tornadoes (including some strong tornadoes), more widespread or severe wind damage and very large/destructive hail could occur. Major events, such as large tornado outbreaks, are sometimes also possible on moderate risk days, but with greater uncertainty. Outbreaks on moderate risk days are not uncommon and typically occur several times a year, especially during peak season. A slight risk area typically surrounds a moderate risk area, where the threat is lower.

Check this thread tomorrow for more detailed information. Stay safe, people!

[phw115wvwx]

Wind appears to be the biggest threat for tomorrow.  You certainly don't see moderate risks by SPC often when it's this late in the year.  Stay safe if you find yourself in a line of storms tomorrow!

[Mr. Rainman]

URGENT UPDATE: SEVERE WEATHER THREAT FOR TONIGHT.


Mainly a wind threat.


All of this severe weather is being triggered by a massive low pressure system with estimated barometric pressures of 960-970 mb (28.35 - 28.65 inches) near its center in Canada. High winds and very severe storms will affect the Northern Plains Tuesday afternoon, and by Tuesday night, several inches of snow and even blizzard-like conditions will exist in North Dakota. This storm, as the Weather Channel puts it, could be the biggest fall storm in 10 to 20 years.

[Mr. Rainman]

Tornado Watch 719 has been issued. Here is all the counties it covers. In effect until 6:00 AM CDT.


Tornadoes and highly severe wind are the primary threats.

[Charismatic Applesauce]

There are a Tornado Watch and High Wind Warning in effect.

Issued by The National Weather Service
Chicago, IL
3:37 am CDT, Tue., Oct. 26, 2010

THE NATIONAL WEATHER SERVICE HAS ISSUED TORNADO WATCH 720 IN EFFECT UNTIL 11 AM CDT /NOON EDT/ THIS MORNING FOR THE FOLLOWING AREAS

IN ILLINOIS THIS WATCH INCLUDES 12 COUNTIES

IN CENTRAL ILLINOIS

LIVINGSTON

IN EAST CENTRAL ILLINOIS

FORD IROQUOIS

IN NORTHEAST ILLINOIS

COOK DUPAGE GRUNDY KANE KANKAKEE KENDALL LAKE IL MCHENRY WILL

IN INDIANA THIS WATCH INCLUDES 5 COUNTIES

IN NORTHWEST INDIANA

BENTON JASPER LAKE IN NEWTON PORTER

THIS INCLUDES THE CITIES OF... AURORA... CHICAGO... FOWLER... GARY... JOLIET... KANKAKEE... MOROCCO... MORRIS... OSWEGO... PIPER CITY... PONTIAC... RENSSELAER... VALPARAISO... WATSEKA... WAUKEGAN... WHEATON AND WOODSTOCK.

Issued by The National Weather Service
Chicago, IL
4:07 am CDT, Tue., Oct. 26, 2010

... HIGH WIND WARNING REMAINS IN EFFECT FROM 7 AM THIS MORNING TO 8 PM CDT THIS EVENING...

A HIGH WIND WARNING REMAINS IN EFFECT FROM 7 AM THIS MORNING TO 8 PM CDT THIS EVENING.

* TIMING... THIS MORNING THROUGH 8 PM THIS EVENING.

* WINDS... WILL SHIFT TO SOUTHWEST THIS MORNING AND INCREASE TO 30 TO 40 MPH... WITH GUSTS UP TO 60 MPH.

* IMPACTS... NON SECURE OBJECTS MAY BECOME AIRBORNE. FALLING TREE LIMBS AND POWER OUTAGES ARE LIKELY... WITH TRAFFIC SIGNALS ALSO EXPECTED TO BE AFFECTED RESULTING IN SIGNIFICANT TRAVEL DELAYS. TRAVEL WILL ALSO BECOME DIFFICULT... WITH HIGH PROFILE VEHICLES BECOMING DIFFICULT TO CONTROL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED OR OCCURRING. SUSTAINED WIND SPEEDS OF AT LEAST 40 MPH OR GUSTS OF 58 MPH OR MORE CAN LEAD TO PROPERTY DAMAGE.

&&

More Information

... DAMAGING WINDS POSSIBLE TODAY...

Today is the 26th, not the 25th.

[Mr. Rainman]

The risk for severe thunderstorms has significantly increased over the last couple of hours. A very rare High Risk day is in effect. Here is the convective outlook.


The chance of tornadoes:


The chance of hail:


And the chance of wind:

[Mr. Rainman]

And finally, the Public Severe Weather Outlook and a definition from Wikipedia:

...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE OHIO AND
   TENNESSEE VALLEYS AND GREAT LAKES...
   
   THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
   DEVELOPMENT OF WIDESPREAD DAMAGING WINDS AND A FEW TORNADOES OVER
   PARTS OF THE OHIO AND TENNESSEE VALLEYS AND GREAT LAKES TODAY
   THROUGH EARLY WEDNESDAY
   
   THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE
   
          EASTERN ILLINOIS
          INDIANA
          NORTHERN KENTUCKY
          SOUTHERN MICHIGAN
          WESTERN AND CENTRAL OHIO
   
   ELSEWHERE...SEVERE STORMS ALSO ARE POSSIBLE FROM THE LOWER
   MISSISSIPPI VALLEY NORTHEASTWARD INTO THE APPALACHIANS AND LOWER
   GREAT LAKES
   
   A POWERFUL JET STREAM DISTURBANCE...WITH WINDS IN EXCESS OF 175
   MILES PER HOUR...WILL MOVE FROM THE CENTRAL ROCKIES ACROSS THE
   CENTRAL PLAINS INTO OHIO VALLEY LATER TODAY AND TONIGHT.
   
   AT THE SAME TIME...AN INTENSE SURFACE LOW ASSOCIATED WITH THE JET
   WILL FURTHER STRENGTHEN AS IT TRACKS SLOWLY NORTHEAST FROM MINNESOTA
   INTO WESTERN ONTARIO.
   
   A COLD FRONT TRAILING SOUTH FROM THE LOW WILL SERVE AS THE MAIN
   FOCUS FOR THUNDERSTORM DEVELOPMENT THROUGH EARLY WEDNESDAY AS THE
   FRONT ACCELERATES EAST ACROSS THE OHIO AND TENNESSEE VALLEYS
   TODAY...AND ACROSS THE LOWER GREAT LAKES AND THE APPALACHIANS
   TONIGHT/EARLY WEDNESDAY.
   
   THE VERY STRONG WINDS ASSOCIATED WITH THE LOW...AND INCREASING
   MOISTURE SPREADING RAPIDLY NORTH FROM THE GULF COAST STATES...WILL
   ALLOW THE THUNDERSTORMS TO ORGANIZE INTO BANDS THAT WILL BE CAPABLE
   OF PRODUCING SWATHS OF DAMAGING WIND AND A FEW STRONG TORNADOES.
   
   WHILE THE GREATEST RISK OF SEVERE WEATHER IS EXPECTED TO OCCUR
   DURING THE DAY TODAY OVER THE OH AND TENNESSEE VALLEYS...A MORE
   LIMITED THREAT FOR HIGH WIND AND ISOLATED TORNADOES WILL CONTINUE
   THROUGH EARLY WEDNESDAY EASTWARD INTO THE APPALACHIANS AND THE LOWER
   GREAT LAKES.
   
   STATE AND LOCAL EMERGENCY MANAGERS ARE MONITORING THIS POTENTIALLY
   VERY DANGEROUS SITUATION. 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.

[Mr. Rainman]

A high risk day indicates a considerable likelihood of a major tornado outbreak or (much less often) an extreme derecho event. On these days, the potential exists for extremely severe and life-threatening weather, including widespread strong or violent tornadoes and/or very destructive straight-line winds (Hail cannot verify or produce a high risk on its own, although such a day usually involves a threat for widespread very large hail as well). Many of the most prolific severe weather days were high risk days. Such days are quite rare; a high risk is typically issued only a few times each year (see List of SPC High Risk days). High risk areas are usually surrounded by a larger moderate risk area, where uncertainty is greater or the threat is somewhat lower.[9]

[phw115wvwx]

Wow, SPC jumped to a high risk for this day!   I'm a little scared to say the least as the expected line of storms has already formed.  There are tornado warnings in effect right now.

[TWCmatthew]

The last time a high risk has been issued was during the Yazoo City tornado. I don't remember having a high risk of severe weather in my area ever.

[Mr. Rainman]

A Particulary Dangerous Situation Tornado Watch is in effect. This is very, VERY close to Chattanooga. I'm literaly shaking a little as I type this.

THE NWS STORM PREDICTION CENTER HAS ISSUED A
   TORNADO WATCH FOR PORTIONS OF
   
          NORTHERN ALABAMA
          MIDDLE TENNESSEE
   
   EFFECTIVE THIS TUESDAY MORNING AND AFTERNOON FROM 930 AM UNTIL
   500 PM CDT.
   
   ...THIS IS A PARTICULARLY DANGEROUS SITUATION...
   
   DESTRUCTIVE TORNADOES...LARGE HAIL TO 1.5 INCHES IN DIAMETER...
   THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE
   POSSIBLE IN THESE AREAS.
   
   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
   MILES EAST AND WEST OF A LINE FROM 60 MILES NORTHEAST OF
   NASHVILLE TENNESSEE TO 55 MILES SOUTHEAST OF TUPELO MISSISSIPPI.
   FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
   OUTLINE UPDATE (WOUS64 KWNS WOU3).
   
   REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
   TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS.
   
   OTHER WATCH INFORMATION...CONTINUE...WW 720...WW 721...WW 722...
   
   DISCUSSION...A PRE-FRONTAL BAND OF CONVECTION CURRENTLY DEEPENING
   FROM N-CNTRL MS NWD TO E OF MKL IS EXPECTED TO EVOLVE INTO TSTMS
   LATE THIS MORNING WITHIN A STRONGLY SHEARED AND
   WARMING/DESTABILIZING ENVIRONMENT.  THE COMBINATION OF EFFECTIVE SRH
   OF 300-400 M2/S2...MLCAPE OF 500-1000 J/KG AND THE POTENTIAL FOR
   MORE DISCRETE STORM MODES SUGGEST A THREAT LONG-TRACKED SUPERCELLS
   CAPABLE OF STRONG TORNADOES.

[toxictwister00]

Isn't it kinda odd that the PDS Tornado Watch is in the South when the high risk is in IL?

[Lightning]

The last time a high risk has been issued was during the Yazoo City tornado. I don't remember having a high risk of severe weather in my area ever.

And that was all the way back on April 24th.

[Lightning]

Here is the tornado watch in effect for my area:

STATUS REPORT #1 ON WW 728

VALID 262045Z - 262140Z

THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.

FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2007

..ROGERS..10/26/10

ATTN...WFO...BMX...

&&

STATUS REPORT FOR WT 728

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS

ALC001-007-009-015-017-019-021-027-029-037-047-051-055-057-063-
065-073-075-091-093-105-107-111-115-117-119-121-123-125-127-133-
262140-

AL
.    ALABAMA COUNTIES INCLUDED ARE

AUTAUGA         BIBB       BLOUNT         
CALHOUN         CHAMBERS       CHEROKEE        
CHILTON         CLAY       CLEBURNE        
COOSA         DALLAS       ELMORE         
ETOWAH           FAYETTE       GREENE         
HALE           JEFFERSON       LAMAR           
MARENGO         MARION       PERRY           
PICKENS         RANDOLPH       ST. CLAIR        
SHELBY           SUMTER       TALLADEGA        
TALLAPOOSA        TUSCALOOSA     WALKER         
WINSTON         
$$


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.

[Mr. Rainman]

Holy crap, tornado spotted near Chattanooga. The sky looks AWESOME!