i was watching the radar just north of milwaukee earlier and i noticed how the storms stopped at a point just northwest of milwaukee.......the whole line stopped but for 3 hours now storms in the oskkosh area just keep backbuilding over the exact same area seems like 20 miles west of Oshkosh hasnt received a drop of rain while the city has been drenched for hours now, is this some outflow boundary that acts like a blowtorch to the east???? i was just wondering if anyone could explain or if they can send me to a link that does..........
Thunderstorms require three ingredients:
1.
Moisture. There must be sufficient
water vapor (typically measured as
dewpoint) to produce
unstable air.
2.
Unstable air. Thunderstorms almost always form in a
"conditionally unstable" airmass. That is, the air
parcel is warmer than its environment after being lifted above its
"Level of Free Convection (LFC)".
Unstable air is typically denoted by a
stability index or positive
CAPE values.
3. A lifting mechanism. This lift is necessary to lift air
parcels to their
Level of Free Convection (LFC). Surface heating often acts to decrease the amount of lift necessary for air parcels to reach their
LFC, but some lift is almost always required. The source of lift is usually
mesoscale, but is sometimes
synoptic scale:
Fronts,
frictional convergence (around lows and troughs),
upslope wind,
gust fronts,
outflow boundaries (generated by previous storms),
drylines,
sea-breeze fronts,
lake breeze circulations, and
valley breeze circulations.
Virtually all
thunderstorms consist of more than one
cell (even
supercells). All three of these ingredients must be met for new
cell growth and the continuation of the
thunderstorm. If not, the
thunderstorm will die.
It appears to me the reason thunderstorm cells continued to "backbuild" over Oshkosh, WI was because
moist,
unstable air was lifted by a
warm front at the intersection of a low level
jet stream.
