Hurricane Willa is battering Mexico’s west coast and will move inland Tuesday night. But this is just the start of its offensive on North America. The storm’s remnants will get drawn into the Gulf of Mexico late Wednesday, initiating its second phase before it ultimately morphs into a drenching nor’easter by the weekend.
Computer models have reached consensus that the storm, infused with Willa’s tropical moisture, will form and is unlikely to miss population centers along the East Coast. Between late Friday and the weekend, windswept moderate-to-heavy rain will stream north from the Mid-Atlantic into New England.
Central Texas will first face the storm’s effects Wednesday as Willa’s remnant moisture surges north of the Mexican border. The National Weather Service predicts one to three inches of rain in central and southeastern Texas, with isolated amounts up to four inches. Although Central Texas was hit hard by severe flooding last week, the Weather Service doesn’t expect the rain to be intense enough or last long enough to cause widespread problems.
Wednesday night into Thursday, Willa’s remnant circulation will emerge in the northern Gulf of Mexico, initiating development of the storm that will soak the East Coast. On Thursday and Thursday night, heavy rain is likely in southern Louisiana, Mississippi and Alabama as well as the Florida Panhandle and southern Georgia, still reeling from Hurricane Michael. Throughout this zone, one to three inches of rain is likely.
By Friday, rain will spread into the Carolinas. As the storm merges with a cold front between Friday afternoon and early Saturday, the nor’easter phase of the storm will be underway, with steady rainfall developing over Virginia, Maryland, Washington and the Delmarva Peninsula.
A raw driving rain is likely throughout most of the Mid-Atlantic on Friday night and into Saturday, edging into New England by Saturday night and Sunday. One to three inches of rain could fall in Richmond, the District, Baltimore, Philadelphia, New York and Boston. Temperatures are forecast to be only in the 40s to low 50s.
Based on the latest-model projections, the rain should end in Washington by Saturday night and in New England by Sunday night.
The storm is still four to five days away from affecting the East Coast, and models differ on its exact track, strength and timing, all of which will have important implications for where the heaviest rain falls and how much, and when it starts and stops.
Compared with Monday, however, models are much more unified on the idea the storm center will track close to the coast or inland, rather than out to sea.
The specifics of the storm track will also determine whether colder sections of the Mid-Atlantic and Northeast, mainly in the mountains, witness an early-season snow event.
The European and American computer models suggest the storm will track from eastern North Carolina over New Jersey and into the interior of New England. Such a track would allow the storm to draw in enough warm air off the ocean to prevent much snow from occurring. Previous model runs had suggested the storm would track farther east, allowing more cold air to spill south.
Additional shifts in the models are possible, but right now the best chance of some wet snow seems to be in the mountains of northern New England, where precipitation may ultimately change to mixed precipitation and rain as mild air pushes northward.
Particularly along the Mid-Atlantic coast, gale-force easterly winds are reasonably likely Saturday, which could raise water levels enough for some minor coastal flooding and beach erosion. While subject to change, the American model projects wind gusts reaching 45 to 60 mph (40 to 50 knots) at the coast and even 30 to 40 mph inland along the Interstate 95 corridor.
Assuming the track forecast doesn’t meaningfully shift, gusty winds up to 30 to 40 mph are also likely in New England on Saturday night and into Sunday, but more from the southerly direction as the storm center jogs farther inland.
When it’s over, the storm’s rainfall footprint is likely to be its most significant feature. From Austin to Boston, one to three inches of rain may fall.
Behind the storm, cool air will funnel south Sunday and Monday. Another weather disturbance riding south along the jet stream could bring more unsettled weather to the Mid-Atlantic and Northeast late Monday into Tuesday. With a colder air mass overhead, the chance of some snowflakes in the mountains will increase with this second wave.