  We search the American Association of Variable Star Observers (AAVSO)
archives of the two best studied dwarf novae in an attempt to find light curves
for long outbursts that are extremely well-characterized. The systems are U Gem
and SS Cyg. Our goal is to search for embedded precursors such as those that
have been found recently in the high fidelity Kepler data for superoutbursts of
some members of the SU UMa subclass of dwarf novae. For the vast majority of
AAVSO data, the combination of low data cadence and large errors associated
with individual measurements precludes one from making any strong statement
about the shape of the long outbursts. However, for a small number of
outbursts, extensive long term monitoring with digital photometry yields high
fidelity light curves. We report the discovery of embedded precursors in two of
three candidate long outbursts. This is the first time that such embedded
precursors have been found in dwarf novae above the period gap, and reinforces
van Paradijs' finding that long outbursts in dwarf novae above the period gap
and superoutbursts in systems below the period gap constitute a unified class.
The thermal-tidal instability to account for superoutbursts in the SU UMa stars
predicts embedded precursors only for short orbital period dwarf novae,
therefore the presence of embedded precursors in long orbital period systems -
U Gem and SS Cyg - argues for a more general mechanism to explain long
outbursts.
