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| PASPC Convective Outlook :Severe Thunderstorms with a tornado or 2. Cannot be ruled out. |
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| Severe Thunderstorms and or Supercells around evening time in the Red River Valley |
SOUTH-EASTERN MANITOBA WILL BE THE FOCUS FOR SEVERE THUNDERSTORM DEVELOPMENT TODAY. AHEAD OF THE TROUGH, MODERATE SOUTHERLY WINDS OF
30 TO 40 KM/H COMBINED WITH A CAPPING INVERSION WILL BUILD DEW POINTS
INTO THE UPPER TEENS OR LOW 20S OVER THE REGION, WITH ADDITIONAL
POOLING IN THE VICINITY OF THE TROUGH ITSELF. THE HUMID CONDITIONS
COMBINED WITH MID-LEVEL LAPSE RATES NEAR 7C WILL COMBINE TO PRODUCE
1500 TO 2000 J/KG OF MLCAPE. WIND PROFILES SHOW STRONG SPEED SHEAR
WITH MODERATE LOW-LEVEL CURVATURE; BULK SHEAR VALUES WILL BE CLOSE TO
50 KT WHILE SRH VALUES ARE FORECAST TO CLIMB ABOVE 200 M/S. ALL
THIS WILL COMBINE TO PRODUCE A MODERATE SEVERE THUNDERSTORM THREAT
OVER THE REGION.
THUNDERSTORMS WILL LIKELY DEVELOP ALONG THE TROUGH LINE LATE THIS
AFTERNOON (SOMETIME AFTER 22Z) WHILE IT LIES OVER THE SOUTHERN
INTERLAKE INTO WESTERN MANITOBA. THE TROUGH WILL LIKELY SUPPORT
SEVERAL DISCRETE SUPERCELLS THROUGH THE FIRST COUPLE HOURS OF ITS
LIFESPAN, THEN FILL OUT INTO A MORE SOLID LINE OF THUNDERSTORMS AS
THE TROUGH PUSHES INTO THE SOUTHEASTERN CORNER OF THE PROVINCE. THE
PRIMARY THREAT FROM THESE THUNDERSTORMS WILL BE LARGE HAIL GIVEN THE
HIGH CAPE VALUES AND FAVOURABLE SHEAR. ANY THUNDERSTORMS THAT ARE
ABLE TO ORGANIZE A SUPERCELLULAR STRUCTURE WILL ALSO BE ABLE TO
PRODUCE DAMAGING WIND GUSTS IN EXCESS OF 90 KM/H. ADDITIONALLY, THE
STRONG INFLOW, HIGH DEW POINTS AND RESULTANT LOW LCLS, AND LOW-LEVEL
HODOGRAPH CURVATURE ALSO PRESENT A LOW TORNADO THREAT. SEVERE
THUNDERSTORM WATCHES AND/OR TORNADO WATCHES WILL BE ISSUED LATER THIS
AFTERNOON AS REQUIRED.
THE GREATEST UNCERTAINTY WITH THIS SYSTEM IS HOW EXTENSIVE
THUNDERSTORM DEVELOPMENT MAY BE; AT THE MOMENT THE IDEAS THAT THERE
COULD BE JUST A FEW ISOLATED SUPERCELLS OR THAT IT COULD GROW INTO A
SOLID LINE OF THUNDERSTORMS ARE EQUALLY BELIEVABLE AND FORECAST
MODELS SHOW THAT, OFFERING A DIVERSE SELECTION OF OPTIONS. IT WILL
LIKELY DEPEND ON SUBTLE BALANCES BETWEEN THE LOW-LEVEL INFLOW AND
MID-LEVEL WINDS AND PRECISELY HOW MUCH THE LOW-LEVEL FLOW BACKS OR
VEERS AHEAD OF THE TROUGH.
THE THUNDERSTORMS WILL EXIT MANITOBA LATER THIS EVENING. MORE SETTLED
CONDITIONS ARE EXPECTED ON FRIDAY.
Information from Environment Canada. Didn't have time to create a post of my own.
https://kamala.cod.edu/offs/CWWG/1907111900.focn45.html
aytime heating, MLCAPE will reach 2000 to 3000 J/kg. The approach of a midlevel speed maximum will increase the bulk shear to 40-50 knots. As a result, supercells are expected during the mid to late afternoon, with the main threats being large hail andThe A low pressure system is forecast to move through central Manitoba, with a surface trough expected to extend to its southwest. South of this system and ahead of the trough, moisture will increase, peaking with dewpoints around 20 C. Coupled with daytime heating, MLCAPE will reach 2000 to 3000 J/kg. The approach of a midlevel speed maximum will increase the bulk shear to 40-50 knots. As a result, supercells are expected during the mid to late afternoon, with the main threats being large hail and damaging winds. The tornado risk will be minimal, as surface winds will be somewhat veered. As the evening wears on, storms are expected to congeal into a broken line and move off to the southeast, out of the region.
