Matt Lanza

Francine starting to organize and turn NNE toward Louisiana, with a slight eastward adjustment today

Headlines

  • Francine is slowly organizing itself today and has turned NNE off the coast of Mexico.
  • The storm is expected to become a hurricane tonight as it tracks toward Louisiana.
  • There has been a minor eastward adjustment to the track forecast today, bringing it in on the east side of the Atchafalaya Basin.
  • Watches and warnings were extended east to Mississippi and Alabama today.
  • Storm surge predictions have nudged up a hair in eastern Louisiana, including Lake Pontchartrain but remain at a 5 to 10 foot peak in central Louisiana.
  • Rain will cause areas of flash flooding across Louisiana and Mississippi in particular tomorrow.
  • Isolated tornadoes are possible from Acadiana through the western Florida Panhandle tomorrow.
  • No other areas of concern to land right now in the tropics.
(NOAA NHC)

Francine now & intensity outlook

After a night of struggles, Francine is putting itself back together today and appears to be on the upswing. Satellite imagery shows a developing core that has eradicated a lot of the dry air that was inhibiting organization overnight.

Francine’s core is beginning to better organize this morning and steady intensification is expected over the next 18 to 24 hours. (Weathernerds.org)

If you look at that loop above, you may be confused by “two” areas of storms. The northern most one is connected. I’m speculating that it may be a predecessor rain event (PRE) due to jet stream interaction downstream of the storm itself. What you should focus on in terms of judging the storm is the core off the coast of northern Mexico, and that’s what’s gradually picking up today. I will say, there is ample dry air over Texas and the Deep South that could continue to impact Francine in some capacity. If the core can close off from this, it has a 12 to 18 hour window to perhaps rapidly intensify before that dry air almost certainly gets involved once more.

European model view of mid-level moisture over the Southern Plains shows Francine likely continuing to pull in some dry air which could limit intensification a bit. (Tropical Tidbits)

In addition, Francine will encounter a wall of wind shear on the Gulf Coast that will help to weaken it quickly once inland. I don’t want to minimize impacts at all, but this will have some challenges in front of it.

So, expect Francine to become a hurricane later today or tonight. It has some chance to get to category 2 intensity, but it is likely to come ashore as a stout category 1. Either way, we’re sort of nitpicking at this point. Landfall is expected to occur tomorrow afternoon with impacts beginning in earnest later in the overnight.

Francine’s track

The forecast track of Francine takes it on a beeline toward Louisiana. There has been some movement to the east this morning in the model guidance which brings it more toward Atchafalaya Bay. Some models even bring it as far east as Houma or Port Fourchon. As a result, tropical storm watches and warnings have been extended east into Mississippi and Alabama now. More on the winds in certain places below.

Francine’s impacts

We continue to see storm surge risk from Francine peaking between Port Fourchon and Grand Chenier at 5 to 10 feet. With the latest forecast update, the surge has been revised upward to the east somewhat, with 3 to 5 feet now in Lake Pontchartrain and along the Mississippi coast. Surge of 4 to 7 feet is expected near Grand Isle to the mouth of the Mississippi River.

Storm surge reasonable peak forecast above ground level. (NOAA NHC)

The rainfall forecast likewise has been adjusted eastward some. We now expect around 2 inches in Lake Charles to as much as 8 to 12 inches in the bays and coast of the Atchafalaya Basin. As much as 6 to 8 inches may fall between Lafayette and Gulfport northward a bit. Flash flooding is possible across southern Mississippi as well. Moderate (level 3/4) risks for excessive rainfall exist in much of those areas near where the storm comes ashore tomorrow.

Rain totals will be highest in the Atchafalaya Basin east into southeast Louisiana and southern Mississippi. (NOAA WPC)

Here’s a revised version of the maximum forecast wind gusts by location today based on currently available NWS forecasts, subject to change:

Houston: 25 mph
Galveston: 31 mph
Beaumont: 25 mph
Port Arthur: 37 mph
Lake Charles: 39 mph
Lafayette: 47 mph
Baton Rouge: 95 mph
Port Fourchon: 55 mph
New Orleans: 45 mph
Gulfport: 45 mph
Natchez: 36 mph
Vicksburg: 32 mph
Jackson, MS: 40 mph
Mobile, AL: 32 mph

The Baton Rouge value is because the storm is expected to pass very near there (the only major city on this list to see that) so gusts of category 1 intensity seem reasonable. This will likely cause some substantial power outages across that region between New Orleans and Lafayette. The drop off in wind to the north of there may be significant, with much less in the way of wind impacts north of I-10/I-12 than south of there.

Isolated tornado risk is a safe bet across much of eastern Louisiana, southern Mississippi, and perhaps southern Alabama and the Florida Panhandle. The region is in a slight (level 2/5) risk of severe weather tomorrow.

A slight risk (level 2/5) is posted from Acadiana through the western Florida Panhandle for severe weather tomorrow due to isolated tornado risk. (NOAA SPC)

Other Francine notes

Houston: For our Houston readers, please see Space City Weather for the latest. There should be no meaningful impacts in the area.

Lower Rio Grande Valley: Heavy rain led to some localized flash flooding issues east of Brownsville to the coast this morning. Rain totals of 2 to 6 inches were estimated by radar.

Rain totals as high as 6 inches or so were estimated by radar at the mouth of the Rio Grande. (NOAA MRMS)

Additional rain may fall today but the worst of the flooding threat should be over here now.

New Orleans: City officials are advising residents to shelter in place during the storm overnight and tomorrow. Significant flooding impacts should not be a serious concern, but localized flooding will likely occur around the city and metro area. Follow local officials in southeast Louisiana and NOLA Ready for the latest local information.

Elsewhere in the tropics

We haven’t been ignoring the rest of the tropical Atlantic, but there’s not a lot to worry over right now. Invest 92L has about a 40 percent chance of developing over the next few days, which is down somewhat. The next area to watch east of there is up to 70 percent over the next week, and there is decent model support for something that may head out to sea.

Tropical development is becoming less likely with Invest 92L, while the area east of there is up to a 70 percent chance. (NOAA NHC)

Otherwise, models are generally unenthused with any areas over the next week or so. It does appear conditions are slowly becoming more conducive for tropical activity late in September. It probably would be a time to watch the Caribbean for any threats. But we’re a long way off from that right now.

Our next update will again be this evening before 9 PM CT with the latest on Francine.

Francine still aiming for Acadiana on Wednesday as a feisty hurricane (UPDATED)

8:15 AM Tuesday Update: We will have more later this morning. Francine is still a tropical storm with 65 mph winds. The revised forecast cone and track is shown here:

Francine’s forecast has not changed significantly since last night. (Tomer Burg)

While Francine is contending with dry air, it remains likely to intensify today into a category 1 or 2 hurricane before coming ashore just past peak in central Louisiana. Impacts have not changed significantly since last night, but we’ll revisit everything later this morning.

Headlines

  • Francine continues to strengthen this evening, and it is expected to eventually intensify into a category 2 hurricane sometime later tomorrow or early Wednesday before leveling off just before landfall Wednesday afternoon.
  • Landfall continues to point toward or just west of Vermilion Bay with only slight adjustments since earlier today.
  • The surge forecast is mostly unchanged with 5-10 feet at peak on the Gulf Coast of central and eastern Louisiana and 2 to 4 feet on Lake Pontchartrain in New Orleans.
  • Widespread flash flooding in Louisiana and parts of Mississippi is likely as Francine moves inland.
  • A localized flash flooding risk exists in the lower Rio Grande Valley this evening and Tuesday morning as Francine passes offshore.
(NOAA NHC)

Francine now

Francine is wrapping up considerably this evening as it begins to approach hurricane intensity. One slight issue Francine is contending with is some dry air that it wrapped in on the southeast side. Could that help cap the potential for rapid intensification into a high-end Cat 1 or Cat 2 hurricane? Perhaps, but at this point it’s just something to watch in the near term and will likely disappear come morning.

Francine took off this afternoon, but its visual presentation has degraded some this evening due to (likely temporary) dry air in the southeast quadrant of the storm. This will likely resolve by tomorrow and should not inhibit intensification. (Weathernerds.org)

Otherwise, Francine is behaving as expected, on the upswing.

Francine track

The track has nudged just a bit to the west through the day today. If we saw it coming ashore on the western side of Vermilion Bay this afternoon, we’re perhaps looking at landfall just immediately west of Vermilion Bay with tonight’s forecast update. In general, this shouldn’t mean a whole heck of a lot from an impacts standpoint, and for all intents and purposes, Francine is on a collision course with central Louisiana/Acadiana/Atchafalaya Basin on Wednesday. Landfall continues to have sped up a bit and now looks to be Wednesday afternoon.

Model agreement is honing in on landfall near or just west of Vermilion Bay in Louisiana. (Tomer Burg)

Francine intensity

This continues to be a challenging intensity forecast. The dry air gives me a little pause, but in general, we expect Francine to rev up to a category 2 storm tomorrow. Could it go stronger? I suppose, but time, land, and shear are challenges it will face that probably keeps that potential low.

As Francine approaches the Gulf Coast, it will run into large quantities of wind shear, which will likely help it to attain peak intensity offshore before approaching landfall. (Tropical Tidbits)

Let’s talk shear for a minute. Recall that in general, wind shear tends to act against hurricane intensification. Francine will have little shear to contend with for the next 24-30 hours or so. But then it’s going to run into a wall of shear on the Gulf Coast. This should allow Francine to peak in intensity offshore and make landfall as a stable or slightly past peak hurricane. This will still cause significant hurricane impacts, but it may shave a little off the top in terms of how bad it could be. That’s good news. It may also allow Francine’s winds to wind down quickly over land as it tracks into Mississippi.

Bottom line: A past-peak category 2 hurricane is expected to make landfall near or just west of Vermilion Bay Wednesday afternoon.

Francine rainfall

The overall thinking with rainfall has not changed much today. We may have seen a slight decline in total rainfall as Francine’s forecast has accelerated and sped up.

The rainfall forecast for Francine has dialed back just a hair, but widespread flash flooding is possible from Louisiana through Mississippi. (NOAA WPC)

Francine will be capable of flash flooding over a broad area from Louisiana into Mississippi.

Francine surge

The storm surge forecast has changed little from earlier today, and we still expect a maximum surge of 5 to 10 feet across coastal parishes between Cameron and Port Fourchon.

Evening storm surge forecast shows little change from earlier today. (NOAA NHC)

Other notes with Francine

I just want to dial up a few other notes on Francine this evening.

Houston: For our Houston readers, a complete update on Francine is on our companion site, Space City Weather. Find it here.

Brownsville: As Francine still has a touch more longitude to “gain” this evening, heavy rain will begin to push into the lower Rio Grande Valley, primarily near and east of Brownsville through South Padre Island and Boca Chica. We could see as much as 6 to 10 inches in spots in this area. While there is likely to be a *very* sharp cutoff between little rain and hefty rain, it will likely be close to the southeast corner of South Texas.

3 to 6 inches with locally higher amounts will be possible through tomorrow in Brownsville and South Padre Island. Lesser amounts up the coast to Corpus Christi. (Pivotal Weather)

Max forecast wind gusts: Here’s a quick summary of the maximum forecast wind gusts from local National Weather Service forecasts in a few of the larger cities in or near Francine’s path as of 7 PM CT Monday. These are subject to change:

Houston: 25 mph
Galveston: 45 mph
Beaumont: 28 mph
Port Arthur: 38 mph
Lake Charles: 43 mph
Lafayette: 69 mph
Baton Rouge: 85 mph
Port Fourchon: 39 mph
New Orleans: 32 mph
Gulfport: 38 mph
Natchez: 44 mph
Vicksburg: 36 mph
Jackson, MS: 57 mph

Our next post will be later tomorrow morning, but we will update the top of this post with any significant changes that may be occurring.

Louisiana coast likely to see significant impacts from Tropical Storm Francine, likely as a hurricane

Headlines

  • PTC 6 is now Tropical Storm Francine with 50 mph max winds.
  • Francine will accelerate north, then northeast over the next 48 hours, likely making landfall in central Louisiana on Wednesday as a hurricane.
  • Francine will intensify, likely peak just offshore of Louisiana, then come ashore steady or slightly past peak, still bringing hurricane impacts to central Louisiana.
  • Interests in the New Orleans metro should continue monitoring for any track shifts, while interests in Baton Rouge, Lafayette, and the rest of central Louisiana should prepare for direct impacts.
  • The Houston area is unlikely to see any serious impacts from Francine.
  • Flash flooding is likely across parts of Louisiana, perhaps into Mississippi and Tennessee, as well as in the Brownsville, TX/South Padre Island areas.
10 AM CT NHC track forecast for Francine. (NOAA NHC)

Francine now

We can retire Invest 91L and PTC 6 from the lexicon. As of 10 AM CT, Tropical Storm Francine has been declared by the National Hurricane Center (NHC).

Tropical Storm Francine is already a formidable tropical storm off the coast of Mexico. (Weathernerds.org)

Francine looks the part for sure. We will have reconnaissance aircraft from NOAA and the US Air Force Hurricane Hunters in there throughout the day gathering additional data on Francine’s center and intensity.

Francine track

Tropical Storm Francine will be broadly steered by high pressure over the Florida Strait which will allow it to track north and then northeast, hence the growing confidence of a track into Louisiana.

Tropical Storm Francine will be steered north, then northeast around high pressure over Florida and Cuba. (Tropical Tidbits)

I have dealt with a lot of tropical systems over the years, and while there is nuance on the where the final landfall point will occur, this is a relatively straightforward track forecast.

For Houston folks: This is likely not a Hurricane Beryl situation where there will be a dramatic last-minute shift into our area (and if that did happen, it would be as a much weaker storm than currently forecast, which judging by satellite imagery today seems highly unlikely).

Tropical model guidance is tightly clustered on a Vermilion Bay landfall right now, but there is a fair bit of risk to the east side of that clustering, opening the door to possible further east adjustments in time. (Tropical Tidbits)

For Baton Rouge and New Orleans folks: This is one you want to watch. If for whatever reason this goes ballistic over the Gulf, it could allow the track forecast to keep shifting east, putting the metro areas in play for significant direct impacts from wind. This is especially true for Baton Rouge, but I think New Orleans should watch things closely.

Francine impacts

Let’s discuss some of those impacts. Francine will come north in an environment that is hospitable to intensification. Expect a steady, if not rapid strengthening (RI) trend with Francine over the next 36 hours. RI probabilities for various thresholds are around 5 to 7 times greater than climatology for this over the next 36 hours. This indicates that there is a good chance this storm becomes a hurricane in relatively short order. Francine will continue strengthening until about Wednesday morning. It will then encounter wind shear values of 20 to 35 kts aloft, which usually will help degrade a storm. This should lead to a peak intensity about 75-100 miles off the Gulf coast, then a steady state intensity or slow weakening on approach to landfall. While it should still come in as a hurricane, it would likely be just past peak intensity.

Winds

For Louisiana, this will likely mean widespread tropical storm to hurricane force winds between about far eastern Cameron Parish and the western fringe of New Orleans. On the current track. If the track shifts east further, this will push east as well.

An annotated map of potential tropical storm and hurricane force winds on land as currently forecast using the European model as a base. This may change before landfall. (Weather Bell)

So folks in central Louisiana should be preparing for hurricane-force wind impacts, while folks in eastern Louisiana should continue to monitor for potential track shifts that could bring them more into play for that. Winds should reach the coast sometime later tomorrow night and Wednesday morning.

Surge

Storm surge is expected to be on the order of 5 to 10 feet at peak above ground level, primarily from eastern Cameron Parish through Port Fourchon. We’re looking at about 2 to 4 feet in Lake Pontchartrain in New Orleans.

Storm surge is forecast to be as high as 5 to 10 feet in Vermilion Bay east to Port Fourchon in central and eastern Louisiana. Surge on Lake Pontchartrain should be on the order of 2 to 4 feet. (NOAA NHC)

This will likely produce some potential damage in central Louisiana and flooding in eastern Louisiana outside of levee protection. Follow local authorities for any details on evacuation orders or preparation tips for Francine.

Rainfall

The good news is that Francine will be moving rather fast, so this could functionally limit how high maximum rain totals get along the track.

Rain totals should peak along and just east of Francine’s track, perhaps as high as 8 to 12 inches in central Louisiana, including the Lafayette area. (NOAA NHC)

That said, it will still produce a lot of rain. The highest rain totals should be in central Louisiana, including both Lafayette and Baton Rouge where 6 to 12 inches of rain is possible. New Orleans should see on the order of 3 to 6 inches. While Houston is currently projected to see 1 to 2 inches, that may be a bit generous.

Notably, while it may generate only a passing mention, the Brownsville area into South Padre Island could actually see a healthy amount of rain on the order of 6 to 10 inches from this as well as Francine organizes offshore over the next 36 hours. Flood Watches are posted there and in southwest Louisiana. We could see additional flash flooding up into portions of northern Louisiana, Mississippi, and Tennessee as well as Francine lifts inland.

Tornadoes

As always, landfalling tropical systems occasionally produce isolated tornadoes, and this storm will be no exception. The risk of tornadoes will be highest between Vermilion Bay and Mississippi, possibly as far east as Mobile Bay as well.

Quick comment on Louisiana metros

As noted above, while the current forecast track will keep the highest impacts in central Louisiana, folks in New Orleans should continue to closely monitor Francine’s progress. Lafayette and Baton Rouge will see strong winds, heavy rain, flash flooding, and potential isolated tornadoes. Scattered to numerous power outages are likely there. New Orleans will see minor surge impacts, flash flooding risk, and some wind. Isolated to scattered power outages are likely, with greater impacts possible if this comes farther east.

Please ensure you’re prepared to deal with some hot weather if you lose power for a few days behind this storm. Forecast highs look to be in the mid to possibly upper 80s on Thursday and Friday after the storm passes. Thankfully, the humidity levels should be near to below average for a couple days.

Elsewhere, we have no tropical concerns as they relate to land.

Our next update will be this evening before the 10 PM NHC advisory, probably around 7:30 PM.

A tropical storm or hurricane is likely in the western Gulf of Mexico this week (UPDATED)

Next update will be after the 10 AM CT advisory on PTC 6 Monday. Changes overnight were minimal with a track toward the Louisiana coast, minimal impacts to Houston, and more significant impacts in central Louisiana. PTC 6 is expected to become a hurricane before landfall.

Headlines

  • Invest 91L is expected to develop into a tropical storm or hurricane in the western Gulf of Mexico by midweek.
  • The track forecast is generally pointed toward the extreme upper coast of Texas or Louisiana.
  • Coastal impacts are likely between Matagorda Bay and New Orleans.
  • Inland impacts will depend on exact track and intensity, but at this point we do not believe Houston is the primary target of this storm.
  • Heavy rain and flooding on the coast is a good possibility.
  • Invest 92L in the deep Atlantic is not a land concern at this time.

Invest 91L to likely become a tropical storm or more in the western Gulf

UPDATE (4:20 PM Sunday): The NHC is issuing advisories on Potential Tropical Cyclone 6. Their first map is shown below, which we telegraphed a bit in the post below from earlier.

(NOAA NHC)

We continue to watch Invest 91L, which is likely to be upgraded to a potential tropical cyclone this evening by the National Hurricane Center. This will probably mean the issuance of tropical storm watches on the Texas and Mexico coasts.

Key messages from the NHC on Invest 91L this afternoon. (NOAA NHC)

The disturbance continues to produce ample thunderstorms in the Bay of Campeche, but it remains a day or so away from actually organizing into a formal tropical entity.

Invest 91L is producing plenty of thunderstorms, but it currently lacks any real organization. (Weathernerds.org)

Look for things to start trying to get in gear later tomorrow.

Track

So where will Invest 91L go once it develops? Some of this will depend on exactly *where* Invest 91L formally organizes. The final track will ultimately be dependent on the intensity which will be somewhat dependent on where it forms, so everything is connected. In general, however, Invest 91L is going to follow the periphery of high pressure centered near Florida.

Invest 91L should basically follow a track briefly NW, then due N, then NE in the western Gulf, which will likely track it toward somewhere in Louisiana. (Tropical Tidbits)

From a forecast perspective, this setup is certainly not without nuance, but it does make the track forecast a little more simple. Initially, 91L will track northwest in the Bay of Campeche. From there, as it organizes, it will begin to turn toward the north. Eventually, it should turn northeast, which, depending on where it forms, puts it on a track likely between Galveston and central Louisiana. Again, there is nuance here in that a weaker outcome would lean left, closer to the Galveston-High Island corridor, whereas a stronger outcome would track a bit closer to Vermilion Bay in Louisiana. But for the most part, I think the track forecast is relatively well understood at a high level today.

The track density of the various forecast ensembles shows a turn to the northeast occurring off the coast of Corpus Christi, sending 91L probably toward Louisiana or the extreme upper Texas coast. Impacts will be felt at the coast in Texas, regardless. (Tomer Burg)

Trends in the last 24 hours have been toward a slightly stronger storm closer to central Louisiana. But there remains a relatively wide berth of possible outcomes. So don’t write it off in Galveston yet, but it is likely that if it hit Galveston directly, it would be a weaker storm.

Intensity

So let’s talk about intensity. Operational modeling has come around to the idea of a more well developed, stronger storm now. Earlier this morning, most tropical modeling was spread between high end tropical storm and low end tropical storm intensity. This afternoon’s runs have tended to bump this up a little, ranging from weak tropical storm to hurricane intensity. SHIPS guidance, which forecasts the odds of rapid intensification suggests about a 6 to 8 times greater than normal potential of this rapidly intensifying in the next 72 hours. Wind shear looks low, and while sea-surface temperatures are not ballistically warm in the western Gulf, they are at or above normal away from the immediate coastline and more than supportive of intensification. It appears the environment will be favorable for intensification.

Based on all this, we are likely heading for at least a moderate to strong tropical storm and a reasonable chance at a hurricane assuming this tracks as shown above toward Louisiana

Impacts

Obviously, we’re going to be concerned with tropical storm or hurricane impacts near and especially east of where this comes ashore, which I won’t try to pinpoint exactly right now, but they’re primarily on the Louisiana coast at this time. We will cover that in more detail tomorrow as more becomes known with respect to track and intensity. We should expect waves of 10 to 20 feet offshore with this as it comes north. Gusty winds will occur on the coast between Matagorda Bay and Sabine Pass in Texas, possibly up to tropical storm intensity (35 to 45 mph). Inland locations like Houston should see much less of that. And again, Louisiana will likely see stronger winds. If the storm comes in at Galveston or High Island, there will be stronger winds in the Beaumont-Port Arthur area.

One of the bigger impacts with this storm will likely be rainfall. Somewhere will likely see 10 to 15 inches of rain from this storm with widespread amounts a little under this elsewhere. For Texas, with a track more to the east, this has generally lowered rain totals there. However, that has led to higher totals in parts of Louisiana. The map below shows the European operational model’s forecast of rainfall. Normally, I don’t care to show operational model guidance rain maps, but I think this is a decent representation of risk. The highest totals will be along track and to the east, but the entire coast, even west of the landfall point should see at least some heavy rainfall.

Rain totals as shown on the European model will likely be highest to the east of the Texas/Louisiana border, possibly extending into Mississippi and Alabama. (Pivotal Weather)

I expect flash flooding to be a concern in Louisiana, which has seen a good bit of rain lately, as well as in southern Mississippi and Alabama. Coastal Texas will be dependent on exact track, but flooding risk doesn’t look overly concerning right now. Still, check in on this again to see if anything’s changed.

Storm surge will also be an issue, but we will await guidance from the National Hurricane Center on that before speculating. And as always, tropical systems can and do produce isolated tornadoes.

At this point, interests on the Texas and Louisiana coasts should continue paying close attention to the forecast updates on Invest 91L or the potential tropical cyclone. The biggest concerns right now are for Louisiana, but continued monitoring is advised in Texas too. More either tonight or tomorrow morning.

Invest 92L

Meanwhile, way out in the middle of the Atlantic, we have Invest 92L, which has 70 percent odds of developing in the next several days.

Invest 92L is going to track generally north, then west-northwest, likely staying out over the open Atlantic. (Tropical Tidbits)

This one will take a day or two to start organizing, but once it does it should track west-northwest, likely strengthening slowly before turning more northwest later this week, probably staying out at sea. For now, interests in the Caribbean islands should keep tabs on this, but it is not currently expected to deliver significant impacts there.

Beyond 92L, we have another wave likely to emerge off Africa later in the week that could develop out at sea in the eastern Atlantic. But there are no other land concerns besides Invest 91L at this time.