Tuesday May 31

[obwan]

From SPC

...UPPER MIDWEST/GREAT LAKES REGION...
REMNANTS OF CONSIDERABLE DAY 1 CONVECTIVE DEVELOPMENT MAY BE IN THE
PROCESS OF SPREADING ACROSS MUCH OF THE UPPER HALF OF THE
MISSISSIPPI VALLEY EARLY TUESDAY. AND THE INFLUENCE OF ASSOCIATED
CLOUD COVER AND PRECIPITATION ON SUBSEQUENT DOWNSTREAM PRE-FRONTAL
DESTABILIZATION REMAINS UNCLEAR. STRONGER LOW-LEVEL CONVERGENCE
ALSO APPEARS LIKELY TO REMAIN FOCUSED NORTH OF THE INTERNATIONAL
BORDER AREA THROUGH THE PERIOD...WHICH MAY ALSO SUBSTANTIALLY IMPACT
THE CONVECTIVE POTENTIAL.

HOWEVER...THE WARM SECTOR BOUNDARY LAYER SHOULD BE SEASONABLY MOIST
/UPPER 60S NEAR 70F SURFACE DEW POINTS/...AND INSOLATION PROBABLY
WILL BE SUFFICIENT TO CONTRIBUTE TO MODERATE CAPE BY THE AFTERNOON.
COUPLED WITH FAVORABLE MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION
EXPECTED TO SPREAD ACROSS EASTERN WISCONSIN AND MICHIGAN NEAR AND
AFTER PEAK HEATING...THIS SHOULD BE SUFFICIENT TO INITIATE NEW
CONVECTIVE DEVELOPMENT. IN THE PRESENCE OF SHEARED 40+ KT WESTERLY
DEEP LAYER MEAN FLOW FIELDS /STRONGEST NEAR AND NORTH OF THE
INTERNATIONAL BORDER/...ISOLATED SUPERCELLS WILL BE POSSIBLE BEFORE
UPSCALE CONVECTIVE GROWTH INTO ONE OR MORE ORGANIZED CONVECTIVE
LINES OR CLUSTERS OCCURS. DAMAGING WIND GUSTS AND HAIL APPEAR THE
PRIMARY SEVERE THREATS...BUT TORNADOES WILL BE POSSIBLE...BEFORE THE
THREAT DIMINISHES/SPREADS INTO ONTARIO TUESDAY EVENING.

from detroit

A STRONG MID LEVEL LOW PRESSURE SYSTEM...CURRENTLY VISIBLE ON WATER
VAPOR NEAR YELLOWSTONE PARK...WILL BECOME NEGATIVELY TILTED AS IT
EMERGES OVER THE NORTHERN PLAINS TONIGHT AND HEADS TOWARDS JAMES BAY
TUESDAY NIGHT. MODELS SUGGEST MUCAPE VALUES WILL REACH 2-3 J/G WITH
0-6KM BULK SHEAR VALUES EXCEEDING 40 KNOTS TUESDAY AFTERNOON AND
EVENING. THERE WILL BE A SUBSTANTIAL CAP IN PLACE AHEAD OF THIS
LOW...WITH CIN VALUES OF 100 TO 200 J/KG. THIS CIN IS FORECAST TO
ERODE TUESDAY AFTERNOON AS DAYTIME TEMPERATURES REACH AND EXCEED 90
DEGREES WITH ASSISTANCE FROM A TROUGH AXIS TRACKING THROUGH THE
CENTRAL GREAT LAKES COINCIDENT WITH THE APPROACHING SURFACE COLD
FRONT. WHILE THESE INSTABILITY VALUES ARE IMPRESSIVE THE MODELS
COULD BE UNDERDOING THE INSTABILITY AS FORECAST DEW POINTS ARE ONLY
IN THE MID 60S. THE MODELS HAVE UNDERFORECAST DEW POINTS TODAY BY
SEVERAL DEGREES WITH MANY LOCATIONS REACHING 70 DEGREES...AIDED BY
THE VERY SATURATED SOIL ACROSS SOUTHEAST MICHIGAN. IF VALUES ARE
AGAIN UNDERDONE FOR TUESDAY CAPE VALUES COULD BE EVEN HIGHER. THAT
BEING SAID IT APPEARS SOUTHEAST MICHIGAN WILL AGAIN BE UNDER A
SLIGHT RISK FOR SEVERE WEATHER TUESDAY AFTERNOON AND EVENING WITH
ORGANIZED CONVECTIVE LINES CONTAINING DAMAGING WINDS AND LARGE HAIL
AGAIN POSSIBLE OVER THE REGION. HIGHS IN ADVANCE OF THE FRONT SHOULD
EXCEED 90 DEGREES...MAKING THE ISSUANCE OF A HEAT ADVISORY POSSIBLE
GIVEN THE SECOND DAY IN A ROW OF WARM AND HUMID AIR.

[Deeon]

sounds pretty convincing :-)

[obwan]

for you guys in the southwest this is from detroit;

0400 PM EDT TUE MAY 31 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL MIDNIGHT. PLEASE SEE
THE LATEST URGEST WEATHER MESSAGE FOR DETAILS.

THUNDERSTORMS ARE LIKELY THIS EVENING. THERE IS A SLIGHT CHANCE THAT
THE STORMS WILL BE SEVERE WITH THE MAIN THREAT BEING DAMAGING WINDS
IN EXCESS OF 70 MPH. LARGE HAIL GREATER THAN 1 INCH IN DIAMETER AND
ISOLATED TORNADOES ARE ALSO POSSIBLE. THE TIME PERIOD OF GREATEST
CONCERN IS BETWEEN 5 PM AND MIDNIGHT. STORM MOTION WILL BE SOUTHWEST
TO NORTHEAST AT 45 MPH.

[DarkSky]

WWCN11 CWTO 312049
 SEVERE WEATHER BULLETIN
 ISSUED BY ENVIRONMENT CANADA
 AT 4:49 PM EDT TUESDAY 31 MAY 2011.
 ---------------------------------------------------------------------
 WATCHES/WARNINGS IN EFFECT FOR SOUTHERN ONTARIO...

SEVERE THUNDERSTORM WATCH FOR:
 =NEW= WINDSOR - ESSEX - CHATHAM-KENT
 =NEW= SARNIA - LAMBTON
 =NEW= ELGIN
 =NEW= LONDON - MIDDLESEX
 =NEW= WOODSTOCK - TILLSONBURG - OXFORD COUNTY
 =NEW= HURON - PERTH
 =NEW= KITCHENER - CAMBRIDGE - REGION OF WATERLOO
 =NEW= MOUNT FOREST - ARTHUR - NORTHERN WELLINGTON COUNTY
 =NEW= GREY - BRUCE.

      POTENTIAL FOR SEVERE THUNDERSTORMS WITH DAMAGING WIND GUSTS AND
       LARGE HAIL THIS EVENING.

---------------------------------------------------------------------
 ==DISCUSSION==
 AS A COLD FRONT MOVES THROUGH SOUTHERN ONTARIO THIS EVENING,
 CONDITIONS WILL BE FAVOURABLE FOR THE DEVELOPMENT OF THUNDERSTORMS
 ALONG AND AHEAD OF THE FRONT.  SOME OF THESE STORMS MAY BE SEVERE,
 WITH DAMAGING WINDS GUSTS EXCEEDING 100 KM/H AND LARGE HAIL
 ASSOCIATED.

REFER TO YOUR LOCAL PUBLIC FORECAST FOR FURTHER DETAILS.

END/OSPC