PDA

View Full Version : Thurs - Fri Aug 19/20


Derecho
08-18-2010, 11:49 AM
Risk of isolated severe weather for Thursday & Friday for southern Ontario. According to the SPC:

Current Day 2 for Thursday

...CNTRL/LOWER GREAT LAKES REGION...
THE COLD FRONT FOLLOWING THE AFOREMENTIONED LEAD IMPULSE WILL SETTLE
SEWD INTO SRN QUEBEC/SWRN ONTARIO AND CNTRL LOWER MI BY THURSDAY
AFTERNOON. A NARROW RIBBON OF LOWER-MID 60S SURFACE DEW POINTS WILL
ACCOMPANY THE FRONT BOOSTING MLCAPES TO 1000-1500 J/KG. COUPLED
WITH HEATING AND MODEST LARGE-SCALE HEIGHT FALLS/ASCENT...SCATTERED
THUNDERSTORMS WILL LIKELY FORM ALONG THE FRONT. WNW MID-LEVEL FLOW
OF 40-50 KTS WILL ENCOURAGE A FEW STORMS TO ORGANIZE WITH AT LEAST
ISOLATED DAMAGING WINDS. ACTIVITY WILL REACH THE LOWER GREAT LAKES
DURING THE NIGHT...BUT THE SEVERE THREATS WILL GRADUALLY DECREASE
WITH TIME/EWD EXTENT.


Current Day 3 for Friday
...UPPER MS VALLEY TO THE LOWER MO VALLEY...
UPPER TROUGH THAT WILL BE IN THE ERN PLAINS/CORN BELT EARLY ON
FRIDAY WILL CONTINUE DOWNSTREAM INTO THE UPPER MS VALLEY AND GREAT
LAKES REGION FRIDAY AFTERNOON/NIGHT. ELEVATED STORMS WILL LIKELY BE
ONGOING EARLY FRIDAY OVER PORTIONS OF THE UPPER MS VALLEY WHICH WILL
LIKELY WEAKEN DURING THE MORNING. IN WAKE OF THE MORNING
ACTIVITY...AIR MASS ALONG/AHEAD OF AN ADVANCING COLD FRONT WILL
BECOME AMPLY UNSTABLE TO SUPPORT POTENTIAL FOR AFTERNOON
THUNDERSTORMS FROM SERN MN/WCNTRL WI SWWD INTO NRN OK. STRONGEST
DEEP LAYER SHEAR WILL EXIST FROM ABOUT KANSAS CITY NEWD INTO WI
WHERE A FEW ORGANIZED STORMS CAPABLE OF DAMAGING WINDS/HAIL CAN BE
EXPECTED. FARTHER S...ALTHOUGH VERTICAL SHEAR WILL BE
WEAKER...BOUNDARY LAYER WILL BE HOTTER AND ISOLATED MICROBURSTS ARE
POSSIBLE. ALL ACTIVITY WILL TEND TO WEAKEN AFTER SUNSET...WITH
LINGERING STORM CLUSTERS AFFECTING THE CNTRL GREAT LAKES AND PARTS
OF THE OZARKS FRIDAY NIGHT.

Derecho
08-19-2010, 02:50 AM
New day 1 is out, hardly worthy anything to talk about.


...LOWER GREAT LAKES INTO NEW ENGLAND...
WITH MID-LEVEL LAPSE RATES NOT LIKELY TO STEEPEN APPRECIABLY
TODAY...PRE-FRONTAL MOISTENING IS NOT EXPECTED TO BECOME SUFFICIENT
TO SUPPORT ANYTHING MORE THAN GENERALLY WEAK INSTABILITY. THIS IS
EXPECTED TO LIMIT SEVERE POTENTIAL WITH STORMS DEVELOPING ALONG AND
AHEAD OF THE FRONT ADVANCING SOUTHEASTWARD INTO THE REGION LATE THIS
AFTERNOON AND EVENING.