Matt Lanza

One-sentence summary

We continue to watch the rain potential from Invest 97L as it tracks toward Central America, while in the U.S., an atmospheric river event will bring locally heavy rain to the Northwest.

Invest 97L: Still watching development chances, but focused more on rainfall

I think we’ve got a bit of a good news/bad news update this morning. The good news is that Invest 97L looks as if it will not be following earlier GFS operational runs, which had this exploding in the southwest Caribbean. Rather, it will be sort of slow getting its act together. The hope is that this will lower the ceiling on 97L’s potential intensity.

In fact, odds of development from the National Hurricane Center have dropped to 50 percent today.

The bad news is that we are still looking at a pretty substantial rain event for portions of Central America, particularly along the coast along the Gulf of Honduras. How much rain? Well, if you believe most model guidance, it should be double digit totals spread out over a few days.

This will be capable of causing flooding, mudslides, and general problems. So regardless of what Invest 97L does, at the very least, it should be a significant rainstorm for portions of coastal Honduras, Guatemala, and Belize, as well as perhaps the southern coastal Yucatan and portions of Nicaragua.

In general, 97L will track west or west-southwest over the next few days on a beeline toward Honduras or Nicaragua. We’ll keep tabs on this over the coming days just in case anything changes and obviously to monitor the flooding risks in Central America.

Elsewhere: Moderate to strong atmospheric river event for the Pac Northwest

Pilar is now on its way out to sea in the Pacific and should no longer be an issue for land.

Some residual rain or localized flooding is possible on the Pacific side of Central America between El Salvador and Costa Rica before things clear out. At this point, impacts from 97L should stay on the Caribbean side of the coast.

Atmospheric river for the Northwest

An atmospheric river (AR) that looks like it should reach level 3 out of 5 on the AR scale will come ashore in Washington or Oregon later this week. ARs of that magnitude are considered strong but offer a general balance of positive and hazardous impacts. Not quite Goldilocks.

Widespread flooding is not expected, but some localized urban or small stream flooding is possible. The NWS in Seattle has identified the Skokomish River near Potlatch as a possible flooding candidate as well. Rainfall totals are expected to be on the order of 2 to 5 inches with round one that comes ashore tonight into tomorrow.

Snow levels will be high with this event, so you will be mainly talking rain below 8,000 to 10,000 feet. A second atmospheric river (a weaker one) will arrive Saturday and perhaps a third round follows Monday. But the more potent one will be tonight into tomorrow. When all is said and done next week, look for about 2 to 5 inches of rain in the Seattle and Vancouver, BC areas, 3 to 5 inches in the Portland area, and higher amounts at the coast and in the Cascades.

Early season chill

Elsewhere, record cold continues in parts of the Appalachians and Deep South tomorrow morning before things begin settling. One impressive record of note may occur in Caribou, Maine which is forecast to hit 12 degrees tonight and Thursday morning. This would be the second earliest date they’ve been this cold. The only time better was when they hit 12 degrees back on November 1, 1972.

Brrr! More tomorrow.

One-sentence summary

Invest 97L in the Caribbean is likely to deliver impacts to portions of Central America in several days, but the exact issues beyond heavy rain and flooding potential remain unclear at this time.

Invest 97L: A troublemaker for the southwest Caribbean

We finally got the Caribbean disturbance a classification yesterday. It is Invest 97L. As we noted yesterday, this one will bear close watching for folks in Central America in particular.

Thunderstorms really popped with 97L overnight, but in the last few hours those storms have begun to steadily weaken. In order for 97L to develop, it will need to be able to sustain thunderstorm activity.

In general, 97L is going to be steered west or just south of west around the periphery of high pressure over the open Atlantic. This will take it on a beeline toward Central America. Unfortunately once it gets there, it looks like it may slow down. This could lead to a considerable rainfall event for portions of the region. In fact both the GFS and European operational models, despite vastly different intensity outcomes each produce nearly double digit rainfall totals through early next week in portions of Central America, particularly near the coasts of Honduras, Guatemala, and Belize.

So we have two aspects of this system that will give us heartburn in the coming days. The rainfall is one, but the intensity of the storm is another. As I noted above, the GFS and European models have been on different planets in terms of what they do with 97L. The GFS continues to be very aggressive, while the European model is far slower to develop the system.

We often get asked “Well, which one do you believe?” The answer is not so simple. The GFS suite tends to develop more persistent thunderstorm activity with 97L, giving it more time to feed on the extremely warm Caribbean waters. The Euro is less excited about persistent thunderstorms at the core, so it remains a rainmaker but not so much a wind-maker. We’ll get a better sense in the next day or so based on the actual speed in organization of the system.

Again, however, the rainfall forecast is already somewhat concerning, so whether or not this becomes a stronger storm will probably not exempt portions of Central America from some noteworthy impacts. We’ll have more on this tomorrow.

Other news: Pilar, record cold, and a wet Northwest

Tropical Storm Pilar will make its 180 degree turn today on approach to El Salvador, shifting back west out into the open Pacific. Conditions should improve in that portion of Central America.

Meanwhile, early season cold continues across much of the country. Quite a few spots will threaten record lows tomorrow morning, ranging from the Ohio Valley into Texas. Places like Oklahoma City and St. Louis are forecast to just eke out new records, while about 35 other locations are within a degree or two of records. Temperatures should moderate for the end of the week.

Otherwise, the only real U.S. weather of note for the rest of the week will be a series of storms into the Pacific Northwest that we discussed a bit yesterday.

One-sentence summary

We’ll be watching the western Caribbean next week for potential development, though any details and specifics are impossible to hone in on just yet.

Tropical Update: Tammy’s ghost, Pacific 92E meanders, and watching the western Caribbean

Tammy’s remnants continue to swirl in the Atlantic this morning, with expectations that it will bend back to the east and out to sea. It is likely to regenerate into a tropical entity today or tomorrow. I wouldn’t say it bears watching, but it could be around in some capacity for awhile in the open Atlantic.

Meanwhile, in the Pacific, Invest 92E is expected to develop over the next several days off the coast of El Salvador. This is not an area with a lot of history of tropical systems. A few smaller systems have impacted El Salvador in the past, mostly tropical storms. However the track forecast for 92E is rather uncertain still, with possibilities of out to sea, a track toward El Salvador or even Nicaragua, or even a drift northwest toward Guatemala or far south Mexico. The current best odds seem to favor a meander offshore of Central America. There will be a reflexive temptation to compare 92E to Otis due to its proximity and south/east placement, but initially there do not appear to be any meaningful similarities. That said, waters here are warmer than average, which will only help with development. Something to watch heading into next week.

Elsewhere, we continue to see rumblings in model guidance toward something trying to develop in the western Caribbean later next week. It’s too soon to say anything with any confidence or certainty, but this would be a place to watch in early November traditionally.

We’ll watch trends this weekend and report back with the latest on Monday.

U.S. Weather: Winter takes hold for a few days in much of the country

The main weather story is precipitation, with heavy rain in the south-central and heavy snow in the north. Snow is likely tomorrow across much of Nebraska, as well as in the Rockies. Snow will spread into the Denver area on Saturday night and into Sunday.

To the south, it’s rain. Yesterday, we noted radar estimates of 9”+ in parts of Texas. More heavy rain fell Thursday in the I-35 corridor and points east to just northwest of Houston. There was even a reported tornado in San Antonio. Additional rain today could cause localized flooding issues.

The highest risk of flash flooding today is probably between Waco and DFW.

That risk of rain will expand north and east as well, focusing southeast of the Tulsa area, much of northwest Arkansas, and southern Missouri tomorrow. Similar areas will be at it on Sunday. Finally, that cold front helping to cause the unsettled weather will shift east after Sunday and Monday, ushering in our first real true Arctic air mass of the season, which could produce record lows next week.

Temperatures are forecast to be in the teens in Kansas City, 20s in Oklahoma City, and mid-30s in Dallas on Wednesday morning, all possible record lows.