Nicole to race by D.C. region Friday, with rain and possibly tornadoes - The Washington Post

Given a batch of atmospheric rotation associated with the remnants of Nicole, a tornado menace besides whitethorn develop. The likelihood of twisters are somewhat higher southbound and southeast of Washington, toward Southern Maryland, Richmond and the Virginia Tidewater.

The National Weather Service Storm Prediction Center has placed the D.C. country successful a Level 1 retired of 5 hazard for tornadoes, portion areas to the southbound are successful a Level 2 retired of 5 hazard zone.

Additionally, the Weather Service has placed the portion successful a Level 1 of 4 hazard for excessive rainfall. The likelihood of dense rainfall volition summation to the westbound and northwest of the D.C. area.

Timing: Shower chances summation during the predawn hours Friday, particularly southwest of the area, and go apt by sunrise. Additional waves of rainfall walk during the day. Rain should extremity precocious Friday night.

Coverage: Expect on-and-off showers, coming done successful waves, and possibly immoderate thunder. The showers volition beryllium fast-moving but whitethorn beryllium rather dense astatine times.

Hazards: The superior concerns are dense rain, gusty winds and a hazard for an isolated tornado oregon damaging upwind gusts. The accidental of flooding is reasonably debased due to the fact that the country has been alternatively adust lately.

Rainfall projections: A wide 1 to 1.5 inches is astir probable. Toward the mountains, 2 to 3 inches could fall. Southern Maryland and the Delmarva Peninsula astir apt spot person to fractional an inch to an inch.

On Friday morning, the halfway of a weakening Nicole volition beryllium implicit cardinal Georgia, arsenic shown below, with showers moving northward done the Mid-Atlantic.

The tempest features a precise ample upwind circulation. High unit retreating to the northbound volition assistance successful tightening the unit gradient crossed the Mid-Atlantic, frankincense keeping upwind speeds elevated. Expect winds to gust often from 20 to 30-plus mph Friday and perchance higher successful immoderate thunderstorms.

As Nicole transitions from a tropical to much of a mid-latitude storm, a lukewarm beforehand volition signifier (red scalloped lines above) that whitethorn beryllium a absorption for immoderate tornadic activity. Meanwhile, a beardown acold beforehand and heavy dip to the pitchy watercourse volition beryllium approaching the East Coast from the Ohio Valley.

The halfway of Nicole’s remnants volition articulation up with that front, possibly adjacent the spine of the Appalachians, arsenic a plume of heavy tropical moisture moves northward to the storm’s east. The beardown uplift connected the westbound broadside of Nicole’s remnants volition interact with tropical moisture to make a swath of perchance precise dense rainfall implicit the Appalachians, with much showery upwind to the east.

By Friday evening, Nicole’s remnants volition rapidly exit to the northeast, and skies whitethorn really commencement to wide by midnight.

While the substance for the types of storms that could make tornadoes volition beryllium constricted successful the D.C. area, the upwind shear (change successful upwind absorption and oregon velocity with altitude) volition beryllium significant. That operation of ingredients whitethorn acceptable the signifier for low-topped rotating thunderstorms. Those cells, successful turn, whitethorn bring gusts of damaging (50-60 mph) upwind to the aboveground successful a mates of spots, arsenic good arsenic make little tornadoes.

Inland tornadoes spawned by tropical remnants thin to beryllium short-lived and weak, but those characteristics besides marque them hard to observe with radar, frankincense hindering the issuance of timely warnings.

At this point, the Storm Prediction Center feels the highest tornado menace volition beryllium conscionable to the southbound of D.C. However, we caution that this portion could widen farther northbound if the aerial wide remains unstable into the precocious day and aboriginal evening hours.

Rain totals volition beryllium highly track-dependent. As of now, astir an inch full successful Washington seems reasonable. A displacement successful the forecast way farther eastbound would bring higher totals person to the area. The portion has been rather adust recently, truthful the threshold rainfall amounts to trigger flash flooding locally are high.

Overall, the predicted way of Nicole’s remnants has shifted west, somewhat lowering imaginable rainfall successful the contiguous area.

Here are the amounts projected by antithetic models:

Additional way shifts are possible, which would impact the rainfall forecast. But we don’t expect large changes, present that we’re wrong a time of the event.