re: Sally - Moving towards Georgia - Potential for Significant Flooding

While northwesterly shear has been affecting Sally, the global
models suggest that the shear will decrease later today as it moves
under a narrow ridge. Models all respond to these changing
conditions by showing intensification, but they disagree on the rate
of change. It is an extremely tricky forecast because of how this
might happen close to landfall, but guidance is generally 5-10 kt
higher than the last cycle so the intensity forecast has been raised
by those amounts up through landfall. It is worth noting that rapid
intensification is a possibility if the system develops a more solid
inner core on Monday, and stronger solutions like the HWRF model
can't be dismissed.

Sally is moving west-northwestward at a faster speed this morning.
The biggest change to note is that almost every model has shifted
westward (faster) due to narrow ridging developing across the
northern Gulf Coast between the storm and an exiting mid-latitude
trough. The flow gets quite weak near and after landfall, so the
cyclone should slow down on Tuesday/Wednesday and turn northward.
After that time, the next trough should induce a faster
northeastward motion by day 5. The new track is shifted westward
between 30-45 n mi near the coast of Louisiana, and is still east of
the GFS and ECMWF models.

Users are reminded to not focus on the exact details of the track
or intensity forecasts, as the average NHC track error at 48 h is
around 80-90 miles and the average intensity error is around 10-15
mph. In addition, wind, storm surge, and rainfall hazards will
extend far from the center. Unfortunately, confidence is increasing
that Sally's expected slow forward speed near the Gulf Coast will
exacerbate the storm surge and heavy rainfall threats.