October 20, 2023 Outlook: Tammy and Norma deliver their impacts this weekend before the tropics quiet down some

One-sentence summary

Tammy will impact the Lesser Antilles with gusty winds and heavy rain this weekend, while Norma clips Baja tomorrow as a fading hurricane.

Tropical Storm Tammy will scrape the northern Lesser Antilles before heading out to sea

Tammy remains a 60 mph tropical storm this morning, and it is one that is struggling a bit to really get itself in a mode to intensify quickly. That’s good news for sure, but a slow intensification remains likely, so Tammy is expected to still become a hurricane over the Leeward Islands tomorrow.

Despite having a very robust area of thunderstorms, Tammy’s center is displaced a bit to the west side of most of the activity, indicating that it’s a formidable but slightly disheveled storm. (Weathernerds.org)

You can see from the satellite image above that the majority of Tammy’s storms are displaced somewhat to the east of the center. This spares most areas for now, but that will likely change as Tammy creeps northwest.

Numerous watches and warnings are posted for the Lesser Antilles and conditions are expected to be at their worst over the next 36 to 48 hours before Tammy lifts north enough to start pulling away.

Tammy is expected to become a hurricane tomorrow as it begins to (slowly) exit the Lesser Antilles. Impacts are likely in the northern half of the island chain. (NOAA NHC)

What to expect in the northern half of the Lesser Antilles? Obviously you’ll see rough surf and some high tides there. Tropical storm force winds will approach from the south and east into tonight and tomorrow. At this time, I don’t necessarily expect much wind to get any farther west than Anguilla or St. Kitts and Nevis. Obviously, continue monitoring Tammy this weekend in Puerto Rico and the Virgin Islands, but for now any direct wind impacts seem minimal to unlikely.

With Tammy’s thunderstorm activity a bit lopsided to the east and a track taking the center near or just east of the Lesser Antilles, the heaviest of the rain will also probably stay east of most of the islands. Still, locally heavy rain is likely with flash flooding a possibility across the northern islands and even perhaps into Puerto Rico and the Virgin Islands as well. There is an elevated risk of excessive rainfall across Puerto Rico today from isolated to scattered thunderstorms. That risk may continue this weekend even with Tammy staying comfortably east of the region.

The European model rainfall forecast shows the axis of heaviest rainfall missing most of the islands, but still anywhere from 30 to 60 mm (1-2″+) of rain falling across the islands, some of which may fall quickly and produce localized flooding. (Weather Bell)

Tammy will exit north of the islands by the end of the weekend. While it’s expected to slowly head out to sea, Tammy might get left behind well north of the islands, allowing it to meander over the open Atlantic. Tammy will intensify further north of the islands until shear begins to enact a toll on Tammy next week. Despite being comfortably away from land, Tammy may continue to produce rough surf on the north-facing shores of the Caribbean islands.

Hurricane Norma has peaked but it will deliver impacts to Baja and Sinaloa

Norma has peaked in intensity and is now slowly weakening. That said, it’s still a category 3 hurricane with 115 mph maximum sustained winds.

Hurricane Norma is beginning to feel the effects of shear and slightly drier air as it comes north and a slow weakening will continue (Weathernerds.org)

Despite this downward trend in intensity, Norma is still expected to be a hurricane as it approaches Baja on Saturday. Norma will come close to making landfall in Baja before curving to the east toward mainland Mexico and coming ashore there as a tropical storm or depression.

Heading to Cabo this weekend? Check ahead to make sure everything is copacetic, but impacts there should be moderate with gusty winds and heavy rain.

Total rainfall of 4 to 8 inches is likely in southern Baja, heaviest to the north and east of Cabo, with another 3 to 6 inches possible on the coast of Sinaloa in Mexico. (NOAA WPC/Google Earth)

Rain totals are shown above for Mexico, with the heaviest rain on the southeast tip of Baja and in coastal Sinaloa.

Winds of hurricane-force are possible in Baja as Norma passes but mostly tropical storm type impacts are expected from wind.

What weather is on our radar for next week?

Next week looks a little more active across the U.S., but the tropics should settle down. Here are the things we’ll be watching.

Tropics: What exactly does Tammy do in the Atlantic? We expect Tammy to go north and out to sea, but as noted above, a handful of models do “trap” it between the Caribbean islands and Bermuda. This would not impact land at all, but it might inject some forecast uncertainty into the picture. Beyond that, we don’t expect any other real notable systems in the Atlantic or Pacific.

Rainfall: There should be a substantial amount of rain with a cold front and some moisture from Norma and the Pacific across portions of Texas into the Plains early to mid next week.

Rain totals of 4 inches or higher are possible in North Texas and Oklahoma near the Red River next week. You can also see this weekend’s heavy rain in the Northeast, locally heavy rain in the Upper Midwest, and the fingerprint of snow risk in Montana above. (Pivotal Weather)

Totals of 1 to 4 inches with isolated higher amounts seems reasonable.

Severe storms: Significant severe weather is not expected next week, but we will keep tabs on the Plains for some isolated potential with a stalled out front in the area.

Snow: There is some potential for a healthy dose of snow in portions of Montana’s mountains, specifically near Glacier National Park and the Lewis Range next Wednesday and Thursday. There’s a slight chance some of that will expand into other high terrain south and east of Glacier late next week.

Heavy snow is possible in portions of Montana midweek. (NOAA WPC)

Temperatures: Ahead of the cold front next week, we have the potential to set some record warm minimum temperatures in the Central U.S. into Texas. Nothing too extreme, but it will not feel like autumn everywhere.

October 19, 2023 Outlook: Tammy toys with the Caribbean islands, while Norma rapidly intensified overnight in the Pacific

One-sentence summary

Tropical Storm Tammy and Hurricane Norma strengthened overnight, but the hope is that most of their impacts will be glancing for the Caribbean Islands (Tammy) and Baja or Sinaloa (Norma) heading into this weekend.

Atlantic Tropical Storm Tammy: Strengthening and will be a close call in the Lesser Antilles

We will start today in the Atlantic, where Invest 94L leveled up to Tropical Storm Tammy yesterday. Tammy now has 60 mph winds after strengthening overnight.

Tammy is strengthening this morning, but its center remains fairly displaced to the north and west of most of the thunderstorm activity. (Weathernerds.org)

I’m not sure I’d classify Tammy as well-organized this morning, but it’s something. Whatever the case, given the higher starting point now, it won’t take much for Tammy to become a hurricane from here. Much of the northern Lesser Antilles are under tropical storm watches this morning. This includes Barbados, Dominica, Martinique, Guadeloupe, Antigua, Barbuda, Montserrat, St. Kitts, and Nevis. With the strengthening this morning, I would anticipate we see watches expanding and some hurricane watches or warnings hoisted later today.

In terms of track and impacts, Tammy will start to turn later today, first west-northwest and then northwest. Given how far south it’s starting from and how far west it already is, it will likely run into the islands before turning northward enough, meaning direct impacts are likely beginning tomorrow. Tropical storm force winds will probably arrive tomorrow morning sometime in Barbados, spreading north and west through the day. Tropical storm force winds would most likely arrive in Puerto Rico and the Virgin Islands on Saturday.

Tropical Storm Tammy is expected to scrape the northern half of the Lesser Antilles. It should track east of the Virgin Islands and Puerto Rico, but impacts are still a possibility there. (NOAA NHC)

A stronger Tammy would be more apt to turn northward a bit faster, so that may be good news for Puerto Rico, which could (should?) end up being spared any kind of meaningful wind impacts from Tammy. Still, it’s close enough, and it’s not as if there will be no impacts. The weather in Puerto Rico looks active the next couple days regardless, with excessive heat in San Juan and the north coast today and some locally strong thunderstorms and heavy downpours today and tomorrow in interior Puerto Rico. Folks should continue monitoring Tammy at least, but the hope is it will be a close miss to the east.

Heavy rain will be possible in the Leeward and northern Windward Islands with anywhere from 2 to 6 inches of rain possible. The heaviest rain will miss to the east as long as the track stays close to forecast. If Tammy does somehow track closer, as much as 8 to 10 inches of rain would be possible for some of the islands.

Beyond the islands, Tammy will continue turning north and head out to sea, looking as if it will pass well south and east of Bermuda at this time.

Pacific Hurricane Norma: Rapidly intensifying but should weaken a good bit on approach to land

Shifting west now, and we’ve had some changes overnight in Norma. As has been the case a couple times this season, rapid intensification outpaced the forecast, as Norma is now a category 3 storm with maximum winds of 120 mph.

Hurricane Norma exploded into a major hurricane overnight with winds now of 120 mph and much more classic looking structure. (Tropical Tidbits)

The good news for land is that Norma is expected to weaken as it approaches the coast of Mexico. So while we have a major hurricane now, should it track toward Baja or Cabo, it will likely not be a major hurricane there. It may still be a hurricane however or close to hurricane intensity as it approaches Baja on Saturday and Sunday. Thus, a hurricane watch was issued for Baja.

Norma is expected to slow down and weaken considerably as it approaches Baja. While it may still be a hurricane as it approaches, it will become a moisture-laden tropical storm with heavy rain possible for the southeast tip of Baja and perhaps parts of Mexico. (Tomer Burg)

Ultimately, Norma’s biggest impact may be rain. Moisture from Norma will spread northward across Mexico and probably into Texas.

Click to enlarge a map of forecast rain through next week from Mexico into Texas and the Southern Plains. (NOAA WPC/Google Earth)

Rain totals through midweek next week may approach 1 to 3 inches in much of interior Texas north into Oklahoma and Kansas. Additional rain may follow late next week with a front. So overall, while Norma is rather potent this morning, the hope is that it will bring mostly beneficial rainfall. That said, interests in Mexico, particularly Sinaloa and Baja should continue to watch Norma’s progress closely.

October 6, 2023 Outlook: Philippe to bring wind and rain to Maine and Canada and even some snow to Quebec and Ontario

One-sentence summary

Philippe will bring a variety of weather to Maine, Quebec, and Ontario this weekend as it transitions to a non-tropical storm and offers up heavy rain, gusty winds, and even some snow in parts of Canada.

Philippe destined to follow Lee’s footprints

Tropical Storm Philippe is a little stronger today as the center approaches Bermuda. Wind gusts over 50 mph were reported on the island this morning. The forecast remains mostly on track, with Philippe essentially being a smaller, less intense version of last month’s Hurricane Lee.

Philippe is in the initial stages of extratropical transition, where it goes from a tropical entity (a storm that derives energy from warm water) to something akin to a nor’easter (a storm driven by jet stream processes and one that will acquire fronts). Storms are displaced east of Philippe’s center today. (Weathernerds.org)

Philippe will likely become post-tropical by tomorrow and transition to a strong nor’easter-type storm as it moves toward the Gulf of Maine or Bay of Fundy this weekend. It is expected to hook back to the north and west across Quebec and eventually stall out on the south end of James Bay, bringing rain and even some snow to Quebec or portions of interior Ontario.

As Philippe transitions to an extratropical storm it will hook back to the north and west across Quebec and settle near the border with Ontario. (Tomer Burg)

The National Hurricane Center will not be issuing tropical products for Philippe as it moves into Canada and New England, indicating that while it will bring impacts they should be managed at the local level. I think a very plain language translation of this means that, while a notable storm, it is not expected to be an especially damaging one. Marine impacts should primarily be gusty winds and large swells. We’re in a lower phase of the tide cycle right now so that helps mitigate that risk a bit.

Rain totals will peak in interior Maine, portions of the Adirondacks in New York, and interior Quebec, where as much as 5 inches of rain is possible. Click to enlarge. (NOAA WPC)

But the main concern with this will likely be tomorrow night and Sunday with locally heavy rain. Total rainfall may exceed 3 or 4 inches in spots, especially in interior Maine and Quebec (north & west of Quebec City, Montreal, and the National Capital Region). Grounds are still fairly damp, so flash flooding is a distinct possibility in spots. Snowfall would be most likely along the Ontario/Quebec border and north of a Sudbury-North Bay line in Ontario.

Watching the Gulf next week

We are starting to see some vague model agreement on next week’s setup with Pacific moisture and tropical noise tracking across Mexico and potentially into the Gulf of Mexico.

The upper level map suggests that whatever happens in the Pacific may get pulled across Mexico next week and into the Gulf, maybe as a lower-end storm, maybe as just a bunch of added moisture. (Tropical Tidbits)

The pattern in the Pacific is such that we should see a bit of a weird entanglement between Tropical Storm Lidia, Invest 99E (the disturbance off the Mexican coast), and an upper level trough in the atmosphere over the Southern Plains and Southeast. How so? In some way, either Lidia or 99E or both will get “pulled” northeast toward Mexico by the upper trough, which will then allow that cluster to track into the Gulf of Mexico. From there, it should probably track northeast or east-northeast across the Gulf toward Florida or the eastern Gulf Coast. What will it be? I don’t know. Probably not a large storm; probably something lower-end. But it could end up being a rain and/or severe weather producer in the Gulf waters or near the coast (or ultimately in Florida). The timing of all this would be late next week. We have a few days to watch this, and we’ll have an update this weekend and on Monday.

Elsewhere, the NHC continues to outline an area deep in the Atlantic that could develop, but it is unlikely to impact land if it does so.

Winter is coming

In addition to the potential snow from Philippe’s remnants in Canada this weekend, we have freeze warnings now populating across the Plains. Freeze watches and warnings extend from northeast Colorado and central Kansas into the Dakotas and portions of western Minnesota.

NWS watches and warnings as of Friday morning shows freeze warnings for more of the Dakotas, Nebraska, and portions of Kansas, Colorado, Wyoming, and Minnesota. Red flag warnings indicating fire risk due to drier air will be posted in the Deep South. (Pivotal Weather)

Low temperatures this morning are in the 20s in spots in Montana but will expand over a wider area on Saturday morning. A warming trend will follow for a time early next week.

Lower Mississippi River dryness

We continue to see the situation in the Lower Mississippi River basin look worse. For Louisiana salt water intrusion to halt or reverse, we need rain upstream; something that can basically flush the salt out. The forecast upriver from New Orleans does not look great, with Memphis likely to see a declining water level over the next 7 to 10 days and most of the Ohio Valley seeing less than half an inch of rain over the next week.

Water levels at Memphis remain near their all-time record lows set earlier this year. (NOAA)

The water level at Memphis this year preliminarily set a new record of -11 feet, and the level by the end of the forecast above has them down to about -10.6 feet again. Hopefully some more meaningful rain can fall around mid-October in the middle Mississippi and Ohio River Valleys, but much more is needed to alleviate the expanding problems in Louisiana. Thankfully at least, the projections for how far north the saltwater wedge gets have slowed considerably.

October 5, 2023 Outlook: Philippe to zip through Bermuda before bringing a nor’easter type impact to Maine, Quebec, and Atlantic Canada

One-sentence summary

Philippe will bring tropical storm conditions to Bermuda tonight and tomorrow before transitioning to a nor’easter-type system and moving into Nova Scotia, New Brunswick, or Maine later this weekend.

Tropical Storm Philippe: Another one for Bermuda & Atlantic Canada/Maine

Tropical seasons tend to have “flavors” to them. And this year’s flavor seems to be that the corridor between Bermuda and Nova Scotia is the highway for quite a few systems. Philippe should join that list.

Philippe will likely bring tropical storm impacts to Bermuda tonight and tomorrow before moving into Maine or Atlantic Canada this weekend. (NOAA NHC)

Over the next few days, Philippe will track northward, probably passing just west of Bermuda tomorrow, which will lead to yet another round of tropical storm conditions on the island. Philippe is not necessarily a strong tropical storm, with winds of 40 mph this morning. But it is expected to gradually become a bit of a broad, more wind-laden system as it tracks past Bermuda and toward Nova Scotia, New Brunswick, or Maine. Ironically, this will be as a result of the storm transitioning (much like Lee did) to an extratropical entity (more like a nor’easter than a tropical storm).

Rainfall over the next 7 days should add up to 1 to 4 inches on average, with a few pockets of higher amounts in Northern New York, Maine, or Quebec. (NOAA WPC)

The main issue from Philippe as it comes north will be gusty winds, rough waves and erosion, and heavy rain as it transitions into a robust non-tropical low over Maine and Quebec. Rain totals are currently expected to be on the order of 1 to 4 inches for portions of New England and Quebec, highest north of Ottawa and Montreal. Localized flooding will definitely be a possibility, and the Weather Prediction Center has northern New England highlighted in their excessive rainfall outlooks for Saturday through Monday.

The specifics on waves and winds will get sorted out in a day or two. But I would expect conditions generally less severe than Lee for Nova Scotia, New Brunswick, and Maine.

What else is out there?

The NHC is highlighting another area in the deep Atlantic that may be able to try to develop next week. Probably nothing, and certainly nothing to worry about at this point.

Closer to land, as Eric noted yesterday, we continue to see some noise in modeling with respect to some moisture off the coast of Mexico. Tropical Storm Lidia will go out to sea in the Pacific, but the next system, closer to the coast of Mexico when it comes west-northwest has a little more complexity.

While Lidia is not expected to be an issue, the area to watch off the coast of Guatemala and Mexico could end up influencing weather in both Mexico and the Southeast U.S. in time. (Tomer Burg)

This one has a chance to drift into Mexico and perhaps into the western Gulf. Should that happen, we could see heavy rain over Mexico or tracking across the Gulf from southwest to northeast. But there’s a long way to go to sort this all out.

Other than that and some strong storms in Texas this morning, we’ll have quieter weather across the U.S. the next few days.