Mesoscale Precipitation Discussion 1052
NWS Weather Prediction Center College Park MD
729 PM EST Fri Dec 14 2018

Areas affected...CNTRL FL...NRN FL

Concerning...Heavy rainfall...Flash flooding possible

Valid 150028Z - 150358Z

Summary...Training line segments to bring a quick 1 to 2 inches to
central Florida while continued convection and stratiform area
brings isolated storm totals close to 4 inches farther north.

Discussion...At least one road closure and other minor flooding
had been reported in and near Ocala, FL. While model guidance had
been indicating an expected weakening trend during the evening
hours, radar and satellite loops as of 00Z suggested training
convection may hold on a while longer. GOES-16 water vapor imagery
showed a very rounded cyclonic flow pattern slowly migrating
eastward - ahead of what GEFS anomalies peg as a 3.0 standard
deviation low at 500 mb. There was no obvious embedded shortwave
structure of the type that would sweep the activity eastward or
cause it to evolve away from the ongoing steady state.

Surface observations of southerly winds and dewpoints in the mid
60s across the FL peninsula support the notion of continued inflow
of unstable air into the ongoing quasi-linear convective system.
The 00Z Tampa sounding measured just under 1000 J/kg surface based
CAPE. Eventually it is expected that deep layer ascent will reform
farther north where the greatest upper difluence meets the warm
Gulf stream. This should gradually veer winds and loosen
convergence over central FL, leading to weakening by 03Z. Until
that time, however, training line segments in a moisture-rich
environment will produce widespread 1 to 2 inch rainfall over a 1
to 3 hour period. This should come up short of flash flood
guidance in most locations, but may cause minor flooding in urban
areas. Additionally, the shield precipitation to the north,
including some continued convective enhancement at times, will
bring storm total amounts closer to 4 inches in the same areas
where flooding had already been reported. Thus, impacts from heavy
rainfall are expected to persist through the evening.

Burke

ATTN...WFO...JAX...MLB...TBW...

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

LAT...LON   30448130 29538063 27378244 27738308 29768224