Michael L. Jurewicz, Sr. WFO Binghamton, NY Northeast Regional Operational Workshop November 5, 2009

AR TC Tracks and PRE Locations All AR TC TracksAll AR PPTC Tracks; with PRE centroids (colored dots)

Mid-level Streamlines Representative TC Tracks TC Rainfall PREs LL θ e -Ridge Axis See inset UL Jet Conceptual Model: LOT PREs Ahead Of SR Or AR TCs Revised and updated from Fig. 13 of Bosart and Carr (1978)

Bill

Brief History of Bill Himself Bill was initially a Cape Verde tropical wave, which became a named storm on 15 August From August, Bill attained hurricane status well off the U.S. East Coast (briefly reached Category 3) From August, Bill transitioned to an extra- tropical system, as it recurved into the westerlies southeast of the Canadian maritime provinces

Bill’s Approximate Path

Heavy Rainfall Event across New England

Afternoon Rainfall on 22 August Up to 7” (175 mm) rainfall

Radar Loop

Water Vapor Loop

250 mb at 12z, 22 August

250 mb at 00z, 23 August

200 mb Height/Wind/PV, 14z, 22 August

200 mb Height/Wind/PV, 22z, 22 August Height Rises / PV Destruction

Surface Analysis, 18z, 22 August Possible PRE

850 mb Moisture Transport Possible PRE

700 mb Heights, 925 mb Winds/Theta-E, at 21z, 22 August Near intersection of Bill’s moisture and pre-existing moist plume

Parcel Trajectories into Central New England Bill’s Track

Bill Summary Bill fit into the AR track for potential PRE-producing systems One main heavy rain episode took place on the periphery of Bill’s influence Southern NH on 22 August 4-7” (up to 175 mm) of rain fell within just a few hours, causing flash flooding Transient nature of heavier rain bands precluded excessive rainfall/runoff problems elsewhere

Danny

Brief History of Danny Himself Danny was initially a Cape Verde tropical wave, and took several days to become a named storm Finally, on 26 August, it attained Tropical Storm status east of the Bahamas From August, Danny remained a Tropical Storm well off the Southeast U.S. coast From August, Danny weakened to a Tropical Depression, and ultimately transitioned to an extra- tropical system, as it recurved off the U.S. East Coast

Danny’s Approximate Path

Heavy Rainfall Event across the Mid-Atlantic Region

Late Night/Early Morning Rainfall, August 4-8” ( mm) rainfall

Radar Loop

250 mb at 00z, 28 August

Water Vapor Loop

700 mb Heights, 925 mb Winds/Theta-E, at 05z, 28 August Axis of tro pical moisture Separate moist axis

850 mb at 00z, 28 August

Parcel Trajectories into the Mid- Atlantic Region

200 mb Height/Jet/PV, 02z, 28 August

200 mb Height/Jet/PV, 09z, 28 August

SB CAPE Analysis, 06z, 28 August

Heavy Rainfall Event Just off the Mid-Atlantic Coast

Late Afternoon/Overnight Rainfall, August Widespread 5-10” (up to 250 mm) rainfall

Radar Loop, August

250 mb at 00z, 29 August

Water Vapor, August

700 mb Heights, 925 mb Winds/Theta-E, at 03z, 29 August Tropical Moisture Axis

SB CAPE Analysis, 00z, 29 August Possible PRE

Surface Analysis, 00z, 29 August Possible PRE

850 mb Analysis, 00z on 29 August

Parcel Trajectories into the Mid- Atlantic Coastal Region Danny’s Track

Danny Summary Danny fit into the AR track for potential PRE-producing systems Two distinct heavy rain episodes took place on the periphery of Danny’s influence Event that most resembled a PRE took place just offshore, August Heavy rain/flash flooding that occurred in the Baltimore area appeared to lack sufficient moisture contributions from Danny or jet interactions Lack of a direct moisture connection with the TC, as well as a relatively cool stable air mass, seemed to protect much of the Northeastern U.S. from excessive rainfall