Mesoscale Precipitation Discussion 0970
NWS Weather Prediction Center College Park MD
1138 PM EDT Thu Oct 11 2018

Areas affected...Mid Atlanic Region

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

Valid 120337Z - 120900Z

Summary...Tropical Storm Michael will move northeast from near the
southern tip of the Delmarva peninsula and eventually pull out to
sea.  Intense rainfall will result in the risk of flash flooding
continuing along the Mid-Atlantic Coast overnight.   Bands of
heavy rainfall are likely to lead to flash flooding, particularly
where they intersect urban areas.

Discussion...As of 03Z, regional radars continued to show a very
strong rain band situated from the southern Delmarva into parts of
far eastern Virginia and southern Maryland. This region was
located to the north of the center of Tropical Storm Michael. 
MRMS and area radars have shown dual pol rainfall estimates that
have occasionally reached as high as 3 in/hr rain rates with this
band. Thinking is that an increasing amount of frontogenesis
should continue to focus a significant rain band into the
overnight hours just north and northwest of the projected path of
Michael's center. This left-of-track rainfall pattern is
consistent with conceptual models of a tropical cyclone
interacting with an approaching front in this way.

GPS-derived Precipitable Water values over the southeast corner of
Virginia and immediately offshore were still around 2.2 inches,
and thus the supply of deep tropical moisture should also be able
to sustain significant rain rates, exceeding 2 in/hr in many spots
and reaching 3-4 in/hr in localized areas. This will lead to
widespread flash flooding wherever the focused rain band
traverses, and is also high enough to potentially lead to more
severe, life-threatening flash flooding.

Elsewhere, along and south of the track of Michael, the tail end
of some inflow rain bands should sweep through the
eastern/southeastern portion of Virginia into the early morning
hours.  These bands should be more progressive and are less likely
to linger in any one spot, but the instantaneous rain rates are
expected to remain high until the instability is swept out of the
area. 

Bann

ATTN...WFO...AKQ...LWX...PHI...

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

LAT...LON   40437328 39537338 38427466 38007526 37917578
            37497625 37267662 36877692 36987739 37897761
            38527732 39027688 39587606 40267453