Mesoscale Precipitation Discussion 0959
NWS Weather Prediction Center College Park MD
936 AM EDT Wed Oct 10 2018

Areas affected...Florida Panhandle & Big Bend, Southwest Georgia,
Southeast Alabama

Concerning...Heavy rainfall...Flash flooding likely

Valid 101334Z - 101800Z

Summary...Heavy rain will become more persistent and widespread as
Hurricane Michael approaches the Florida Panhandle coast today.
Rainfall rates to 3 in/hr will likely lead to flash flooding in
some areas. Rainfall totals may exceed 4-5 inches by 1 PM CDT
along the immediate coast near where Michael approaches landfall.
Additional rainfall would be likely beyond that time.

Discussion...Hurricane Michael continues to move toward the
Florida Panhandle coast this morning. Some initial low-topped
convective clusters and rain bands in the Florida Panhandle have
produced around 0.5 to 1.0 inches of rain in 15-20 minutes per
several WeatherSTEM mesonet sites. However, these more intense
rain rates have generally not been sustained for more than a half
hour so far at any specific location as the rain bands have been
somewhat discontinuous. That may begin to change over the next
several hours as low-level convergence naturally begins to
increase over the central Florida Panhandle and Big Bend. This
will be due to a combination of speed convergence (as the stronger
winds in the inner core begin to approach) and wind direction
variation (with winds more backed in the I-10 corridor inland
given frictional effects). This may begin to produce some more
solid rain bands arcing in off Apalachee Bay, with an attendant
increasing risk of flash flooding. Furthermore, the inner core of
Hurricane Michael is likely to draw much closer to the coast in
the next several hours. Heavy rain bands and eyewall convection
should be more sustained in this portion of the storm, which would
enable longer durations of heavy rain rates as that reaches the
coast. Therefore, through 18Z there will be a small area near the
eventual landfall point where rainfall begins to accumulate at a
more rapid pace, and totals could exceed 4-5 inches by 18Z. The
combination of the arrival of inner core convection and increasing
convergent rain bands should increase the flash flood threat in
the Florida Panhandle and Big Bend in the next several hours.
Further to the north, rain bands will begin to increase in Alabama
and Georgia, but flash flooding is less likely there prior to 18Z
given the increasing distance from the center of the hurricane and
a lack of obvious strong low-level convergence that far north.

Lamers

ATTN...WFO...BMX...FFC...JAX...MOB...TAE...TBW...

ATTN...RFC...SERFC...

LAT...LON   32188620 32098467 31068342 29828279 28948288
            29768401 29488521 30068583 30328652 30278742
            31228721