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Powerful Pacific System Impacting the West; First Significant Snow for Portions of the East

Power Pacific system will continue to bring significant impacts for Pacific Northwest into northern California the remainder of the week. Dangerous coastal affects, heavy rain, flooding, strong winds, and higher elevation mountain snow continues. Meanwhile, a storm across the east is set to bring the first accumulating snow to many higher elevations of the Catskills into the central Appalachians. Read More >

Overview

General Summary: Tropical Storm Elsa made landfall on the west coast of Florida during the morning of July 7 (Wednesday). Elsa then tracked north-northeastward through Georgia and the Carolinas from Wednesday through the first part of the day on Thursday, July 8. Elsa then tracked to the north-northeast across eastern Virginia and the Delmarva Peninsula as a low-end tropical storm from the evening of July 8th to the early morning on Friday, July 9th.

Some wind impacts (due to gusts of 40-50 mph, with a couple gusts as high as 60 mph) were felt across eastern VA, northeast NC, and the Lower Eastern Shore. Localized power outages occurred, but impacts were far less than what was observed during Isaias in August 2020, when 300,000 people were without power at one point. However, there were some significant flood/flash flood impacts (generally along and just to the left of the track). A swath of 2-5” of rain was observed from Mecklenburg/Lunenburg Counties to southern/eastern portions of the Richmond Metro to Dorchester County, Maryland. There was one report of just under 6" of rain in Chesterfield County, VA. The most significant flooding from Elsa in the AKQ CWA occurred Thursday evening when 70% of all roads in the City of Petersburg were closed at the height of the event (see the Flooding Reports section for a list of reports). This was in addition to several reports of flooding/flash flooding across the area. Five tornadoes (all EF-0) touched down across SE VA and NE NC. Minor tidal flooding was observed on the north side of the Albemarle Sound and on the bay side of the Lower Maryland Eastern Shore.

Tornadoes: As Elsa tracked to the NNE through the area late Thursday afternoon into Thursday evening, slightly drier air surged in from the west-southwest (see T-Td-Wind loop in environment section for more detail). This created a boundary between the moist air to the northeast and dry air surging in from the west-southwest. On the east side of the boundary, winds were mainly out of the SE with temperatures in the mid to upper 70s to and surface dew points in the mid 70s. To the west of the boundary, winds were generally out of the southwest with slightly lower dew points. As is typical with tropical storms, the boundary layer wind fields were relatively strong and the best low-level speed/directional shear was located to the right of the track of the system. Along and just east of the track, slightly veering (and increasing) winds from the surface to 925 mb allowed for 0-1 km SRH values to climb to higher levels (locally 200-350 m2/s2) in an area roughly to the east and northeast of the center of Elsa. This combined with modest instability (500-1000 J/kg to the E/NE of the center on average) resulted in an environment favorable for brief, spin-up tornadoes. Interestingly, around/just before 4 PM, there was one mini supercell that exhibited very strong rotation (reminiscent of the supercells that produced EF-2 tornadoes during Isaias in August 2020) that tracked northward across Bertie/Hertford/Gates Counties in NE NC. This supercell was well to the northeast of the boundary between the moist and slightly drier air and failed to produce more than a weak EF-0 tornado despite having a well-defined, deep mesocyclone with rotational velocity values of 40 to 45 knots.  When a rain band just ahead of that slightly drier air at the surface (and likely on the leading edge of some drier air in the mid-levels) tracked across SE VA and NE NC from 7 to 9 PM, 4 additional EF-0 tornadoes touched down across the area (from embedded rotating cells along that band). However, none of the cells along that band contained a mesocyclone that was as strong and deep as the one that was observed in that mini supercell just around/before 4 PM. One other difference in the environment between 4 PM and 7-9 PM that was noted by forecasters that worked the event was that LCLs were a few hundred meters higher during the late afternoon than during the evening.

Tidal Flooding: The fast track of Elsa (and the fact that it was a low-end tropical storm as it crossed the area) greatly limited the impacts from tidal flooding. Minor tidal flooding was observed in areas along the north side of the Albemarle Sound (from Edenton to Elizabeth City) during the evening of July 8th due to the elevated SE to SSW winds. Minor flooding was also observed on the bay side of the Lower Maryland Eastern Shore during this time. 

*All tornado data is preliminary and subject to change.

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