Overall rainfall amounts Monday should be light, but modest enough to help
resaturate the ground after several days of dry weather. As the
shortwave moves quickly eastward, the second round, which is
associated with an area of low pressure, arrives Monday night
through Tuesday morning. Much better precipitable water values
accompany this round of widespread rain, increasing concern for
higher rainfall amounts and the potential for flooding. With
essentially no break following round two, the most concerning round
of rain arrives Tuesday night into Wednesday. A deepening trough and
intense vorticity maxima moves into the Ohio Valley with deepening
surface pressures and plentiful moisture. Precipitable water values
(1.2-1.3 in) are easily within climatological records for the first
week of March and pressure anomalies are two to three sigma lower
than the normalized mean. With these factors all combining with
intense vertical lift, the heavy rain/flooding signal is
understandably alarming. The Climate Prediction Center has also
placed the Ohio Valley under a 50-60% confidence for above average
rainfall for the 6-10 day period. By examining the individual
members of the latest 00Z guidance, the axis of heaviest rain still
ranges from NW of the Ohio Valley to well southeast across the
Tennessee Valley, however at this time, the highest probabilities
are aligned with the Ohio Valley. Fortunately, there is still time
for details to be ironed out and for things to change, but enough of
signal was observed with this forecast package to note the
potential.