Matt Lanza

One more round for California, and the first major hurricane season outlook was unveiled Wednesday

Today we’ll touch on some rain in the West, an update on the eclipse cloud cover outlook, and have some comments on early hurricane season outlooks.

Headlines

  • Moderate SoCal flash flooding risk with one of the wet season’s final big storms.
  • Still signals for a storm system “in the neighborhood” of the path of totality for April 8th’s eclipse, but confidence is not really any higher.
  • AccuWeather released their hurricane season outlook on Wednesday, calling for 20 to 25 named storms and 8 to 12 hurricanes, a very active season.

It does rain in Southern California

Let’s begin out West where a gnarly late season series of storms is helping to “top off” California’s snowpack and deliver one more round of rain to Southern California. One storm is exiting the Sierra today. The next one actually tracks southeast along and off the California coast, where it will bring a round of heavy rain and chance of thunderstorms to SoCal.

The 50th percentile snowfall forecast (consider this a rough guide for an average model forecast) from the Weather Prediction Center shows about 1 to 2 feet of snow in the Sierra, with at least a little risk for more through Sunday morning. (NOAA WPC)

As far as rain goes, it looks like the LA Basin will do well in this one with an inch or two of rain for most. Heavier totals (and some snow, with snow levels perhaps as low as 4,500 feet at times!) will be possible in the LA County and Ventura County mountains, as well as out toward Santa Barbara. San Diego will also do well in this one with 1 to 2 inches of liquid expected. Isolated higher amounts are possible, as is flash flooding in some of these areas.

Rain totals through the weekend will be impressive for early April in SoCal, with 2 inches or more possible in spots between the Central Coast and San Diego.

The storm hits Saturday and exits later Sunday, setting up perhaps some quieter weather next week. In addition to rain, there will be some thunderstorms with perhaps the usual California rogue, localized tornado possible.

This storm will emerge in the Plains next week and bring the potential of locally heavy rain and even some more snow to parts of the Central and Eastern U.S., including snow or ice potential in New England next Wednesday or Thursday.

Do we know anything further about the weather for April 8th’s eclipse?

Do we have any clarity on the forecast for the solar eclipse today? Not really. Back on Monday we noted that model ensembles were suggesting a storm exiting the Rockies and some noteworthy precipitation probabilities on the Gulf Coast and in the Midwest. Everything remains pretty status quo today versus Monday.

Monday, April 8th’s midday probabilities of rain are highest still along the Gulf Coast and up into the Mississippi Valley. The eclipse totality path, in addition to other percentages of coverage are overlaid. (Tomer Burg)

Keep in mind that higher rainfall probabilities do *not* necessarily mean it will be overcast. As is often the case, we could have scattered or broken clouds which could still allow for eclipse viewing, even if rain chances are relatively high.

If we could say something of note that’s changed, I might point to the expected system exiting the Rockies. Overall, 500 mb heights are a little less low, which indicates that perhaps the storm system emerging will be a bit weaker? Too soon to say much in that department. But suffice to say that things have not trended much worse since Monday, so that’s good news at least.

The weather pattern 20,000 feet up (500 mb level) shows the trough closer to the Four Corners than Plains, which may help serve up a weaker system in the Sunday-Tuesday timeframe around the eclipse? (StormVista)

Also, shout out to Tomer Burg and StormVista for enabling the eclipse path overlay on their sites. Helpful!

I know some people think this exercise is silly; Matt, you’re devoting a whole section of your post to say “we don’t know.” And you’re correct, we are doing that. But the interest in this forecast is astronomical (pun intended). We are here to give the people what they want!

Anyway, let’s check back in on this on Saturday or Monday.

Here come the big hurricane season outlooks

According to the Barcelona Supercomputing Center’s aggregator of seasonal hurricane forecasts, we have had two as of yesterday: Weather2020 predicts 14 to 19 storms and 8 to 10 hurricanes. StormGeo predicts 21 named storms and 11 hurricanes. Yesterday, AccuWeather published their forecast calling for an “explosive” (their words) hurricane season in the Atlantic. They project 20 to 25 named storms and 8 to 12 hurricanes. They also go on to note that their analog years suggest the Texas coast, Florida, and the Carolinas are at a higher risk than usual this year. Analog years can be fickle, and recall that it is difficult to predict exactly who will get hit before the season begins. Just last year, AccuWeather noted that the entire Florida coast and Southeast coast was at a higher risk than usual, with a lower risk in the Northeast and Texas. While Florida did see Hurricane Idalia and the Carolina coast Tropical Storm Ophelia, the Northeast flirted with Hurricane Lee, while Texas saw Tropical Storm Harold. My point is analogs can produce mixed results.

I don’t take issue with their forecast at all. I do take issue with using the word “explosive” to characterize it for a headline, but that’s a battle we’ll probably continue to lose.

Anyway, we warned you earlier in the month that as these forecasts are released, they will likely be big. AccuWeather is the first major forecaster to tee one up. The next one up should be Colorado State University, generally the gold standard of these sorts of things. Their first outlook will be released next Thursday. We will have a full recap of that next week. Continue to expect some bulled up forecasts.

Digging into the model data to tell you what we know about the weather for April 8th’s solar eclipse

Keeping it simple today: We’re going to discuss what we can say with any degree of confidence right now regarding the solar eclipse forecast for April 8th.

Spoiler alert: This looks a bit complicated.

Everyone, I mean, like everyone wants to know what the weather will be for the solar eclipse next month. So, what can we realistically look for this far in advance with respect to April 8th around midday? Well, yes, we can look at raw model data such as that offered by the GFS operational model.

GFS operational model’s deterministic cloud forecast for 4/8 at midday. Not much value in using this as a planning tool right now. (Pivotal Weather)

That doesn’t tell us much of value, but, hey, it’s a forecast.

Sidebar: It seems a little counterintuitive, so why do we keep saying that one of the top tier weather models isn’t telling us much of value? We do this with hurricanes too. What gives? Operational models are deterministic guidance. They’re giving us one solution. Once you’re out beyond 7 to 8 days, a tool giving us one solution has limited value. Yes, it could show something relatively correctly, but most of the time it will miss on details. That’s where ensemble guidance comes in and is so useful. Why look at one run with one solution when we can look at one run and get 30 solutions or 50 solutions? Ensemble guidance allows us to do this, as it tweaks the model each time it runs. It gives a more realistic portrayal of what could happen, as well as what the risks may be. You get both a mean of 30 to 50 different outcomes, and you also can interrogate the model “under the hood” somewhat as well. And that’s what I plan to do with respect to the eclipse.

Clouds can happen in multiple ways. You can have a broad storm system that shoves a deck of cirrus and stratus clouds over you, creating a solid overcast. You can have some fair weather clouds ahead of or behind a storm system also. Those latter types are far too difficult to predict this far in advance. While those probably won’t wreck the eclipse viewing in any given spot, they could temporarily thicken up enough to cause some issues. Notably, those types of clouds also tend to form via heating of the day, so as the sun disappears behind the moon’s shadow, so may any fair weather clouds. We saw this happen in August 2017.

But what I will focus on in today’s post is the broader storm potential. Namely: How much of a chance is there that a large storm (like the one we experienced this past weekend and yesterday) will wreck solar eclipse viewing on or near the path of totality? To answer this, the first thing I want to look at is how many ensemble members have a surface low pressure system somewhere in the vicinity of the totality path.

The European ensemble suggests some type of surface low of some intensity somewhere between the Plains and Canada on Monday the 8th. While this is helpful, it’s not particularly useful yet as placement and intensity matter. (Tomer Burg)

Let’s start by looking at what the European ensemble model is showing in terms of individual low pressure centers on April 8th around midday. Underlaid on the map above from Tomer Burg is what we call the “interquartile range,” or IQR. This is the difference between the 75th minus the 25th percentile of ensemble mean sea level pressure. The greater the value, the greater the IQR, the greater the uncertainty. And indeed, you can see from that map that there is a fair bit of uncertainty, particularly from the Plains into the Great Lakes.

So initially we can say that there is a fair bit of uncertainty with regard to the potential for there to be a storm system over the Central U.S. Most of these ensemble members look weak, but the disagreement is such that we can’t say anything with any real conviction yet, other than there seems to be some potential for a system.

Let’s look at precipitation probability. In the weekend prior to the eclipse, precipitation probabilities (for any precip greater than 0.01″) are rather low right now across the center of the country. By Monday, those probabilities actually increase somewhat. In fact, the ensemble probability of at least 0.01″ of rain is greater than 50 percent over parts of Missouri, Iowa, and Illinois right now. Does that mean it’s definitely going to rain? No. Right now, we’re just gathering data.

The probability of precipitation on Monday the 8th currently sits around 40 to 50 percent on the European ensemble for the Gulf Coast into Arkansas, as well as in the Great Lakes and parts of the Midwest. (Tomer Burg)

If we look at the upper levels of the atmosphere, it appears we do have a negative 500 mb normalized height anomaly over the Rockies and into the Plains. What? If we look up about 20,000 feet in the atmosphere, it appears there is some sort of weak system trying to push out of the Rockies around the day of the eclipse.

A weak upper level trough may be exiting the Rockies around Monday the 8th, which could support the idea of a low pressure system at the surface east of there. (Tomer Burg)

So let’s put this all together:

  • Euro ensemble model showing a good deal of uncertainty, as well as several generally weak low pressure systems in its 51 members over the Central U.S.
  • A probability of precipitation in excess of 40 percent on the ensemble mean in portions of the Gulf Coast and Midwest/Lakes.
  • An upper level pattern that suggests a system could be emerging out of the Rockies around that time.

None of those data points tells us anything with certainty. But the initial takeaway on this from my perspective is that there may be some parts of the path of totality that will be dealing with cloud cover on the day of the solar eclipse. Exactly where? We don’t know. We’ll check back in on this in a couple days and see what has changed.

Northeast blasted, more snow coming to the Central U.S., and a way too early solar eclipse preview [Updated]

The storm in the Northeast and Mid-Atlantic yesterday absolutely blasted parts of the interior with heavy snowfall; a very impressive late March storm. There’s more winter coming, as it seems we’re making up for a winter of little winter now in spring. A tip of the cap to the groundhog who missed this one. Today’s post also explains how we’ll be looking at the forecast as it relates to the solar eclipse on April 8th. (Post updated with new details on severe weather chances today and tomorrow)

Headlines

  • Northeast snow was impressive; we recap totals.
  • Next storm will dump snow in the Plains, Upper Midwest, and Ontario.
  • Fire weather danger and powerful winds in the Southern Plains from this storm.
  • Severe weather possible as well.
  • Another storm next weekend?
  • The way too early eclipse preview and what we’ll be seriously watching over the next few days with respect to that forecast.

Digging out in New England

Landgrove, Vermont checks in this morning as the champion of yesterday’s massive interior snowstorm. They received 32 inches of snow there, with other parts of Vermont, New Hampshire, and Maine seeing amounts that were also impressive: The White Mountains south of Conway, NH seeing 28 inches, 27.3 inches near Ludlow, VT, White River Junction in the Connecticut River valley seeing north of 26 inches, and Bryant Pond, ME seeing 25 inches.

Snowfall analysis from yesterday’s storm in New England, which brought a wide swath of 12 inches or more from the southern Adirondacks into Vermont, New Hampshire, and interior Maine. (NOAA)

The totals were impressive in valley locations to be sure. Typically in March, there’s a strong elevation bias in snowstorms in New England or the Adirondacks. That really was not the case yesterday. This was just a dump of moisture, as rain totals south of the snow were also impressive. Places like Philadelphia saw their wettest March day and wettest 24 hour period in March on record, dating back to the late 1800s. So for those of you that like snow, congratulations!

What’s coming next?

The next winter storm will dump a substantial amount of snow today and tomorrow in the northern Plains and Upper Midwest.

Snow totals over the next 24-48 hours will be in the 10 to 14 inch range across extreme northeast South Dakota into much of northern and central Minnesota, with some enhancement possible north of Duluth. (Pivotal Weather)

Snow totals of 25 to 45 cm will occur in Ontario, including Thunder Bay as well.

This will be a significant storm for the region, with blizzard warnings posted south of here from southern South Dakota into interior Nebraska and extreme northwest Kansas; also just south of Denver too. Wind gusts of 60 mph or stronger are possible in those areas, which when combined with snow will probably produce blizzard conditions. Remember, the amount of snow that falls is not a condition required to meet the definition of a blizzard. It has to do with visibility and wind: At least 3 consecutive hours of falling snow, low visibility below a quarter-mile and sustained winds or frequent gusts over 35 mph.

Forecast maximum wind gusts late today and tomorrow in the Central Plains. (Pivotal Weather)

Working our way south, these type of wind gusts will contribute to critical fire weather danger today in the Texas Panhandle and Permian Basin south to Big Bend.

Critical fire weather danger is forecast from southwest Kansas to Big Bend in Texas. (NOAA SPC)

Red flag warnings and high wind warnings are posted all over this area, with wind gusts of 55 to 65 mph and relative humidity at 15 percent or less.

Not to be outdone, severe weather is a possibility from portions of Kansas and Oklahoma into Texas today, shifting east into the Lower Mississippi Valley tomorrow.

(Update: 1:30 PM CT Sunday): The NWS has increased severe weather risk for the rest of today, as well as tomorrow for portions of the Plains and Lower Mississippi Valley.

An enhanced risk (level 3/5) is in place for Kansas and Oklahoma this afternoon, primarily for severe hail but also due to damaging winds and tornado possibilities as well. (NOAA SPC)

An enhanced risk was added to southern Kansas and northwest Oklahoma for today. It seems that ingredients for severe weather are coming together a bit more vigorously in this region than expected. In addition to the risk of damaging winds and isolated tornadoes, there will be a good risk for big hail today in parts of the enhanced risk and adjacent areas.

Meanwhile, the severe risk was also upgraded to an enhanced risk tomorrow (level 3/5) for potentially strong tornadoes in portions of Louisiana and Mississippi.

An enhanced risk (level 3/5) was also added to the forecast for Monday in the South. Emphasis is placed on tornado risk in portions of northeastern Louisiana and Mississippi. (NOAA SPC)

Tonight’s storms will weaken, but as the system moves east, look for storms to reintensify tomorrow along the Sabine River at the Texas/Louisiana border, likely peaking north and east of about Alexandria, LA, with a chance for both individual supercells and more of a messy squall line. Both types of storms will be capable of producing tornadoes, in addition to strong winds and perhaps some hail.

There will also be a lower-end severe hail or wind risk in parts of Iowa tomorrow as well.

Is that it? Are we done?

Perhaps not. There’s another storm aiming for the 30th and 31st, next weekend. Details are extremely fuzzy on this right now, but it’s being highlighted by the Climate Prediction Center as having a potential to produce heavy snow next weekend.

Another significant storm is possible next weekend, although details are extremely fuzzy. Still, heavy snow may repeat in parts of the Plains, with strong winds as well. (NOAA CPC)

Looking at model guidance, there’s definitely a storm signal on all the relevant operational model guidance, though none seem too crazy right now. Still, when looking at ensemble guidance to get a sense of the spread within the model guidance, there’s a healthy amount of uncertainty in terms of track and intensity. So we’ll watch this through the week.

A wayyyyy too early eclipse preview

Good news and bad news today: The good news is that our model guidance reaches out to Eclipse Day on April 8th!

The GFS 372 hour cloud forecast is essentially useless. But it’s out there, so here’s what it says about the eclipse day. Note: Blue indicates clouds; white indicates clear conditions. (Pivotal Weather)

The bad news is that it’s really just the GFS operational model, and it tells us nothing of planning value with respect to the eclipse. What we’ll be watching for this week will come primarily from ensemble model guidance. What I want to know this week is what the odds are of a storm system somewhere along the path of totality. That will give me some confidence in terms of how I feel about cloud risks. While clouds are such small scale features that they’re virtually impossible to forecast at a level that matters for eclipse viewing until we’re within hours or a couple days of the eclipse, we can at least start placing some odds on areas that could be troublesome and areas that may be less troublesome come Monday the 8th. We’ll be updating this a couple times this week and probably daily next week. Stick with us for the latest!

Winter’s grip lingers in the North, while the East Coast sees yet more rain

Today, we take a look at what’s happening with our two main storms over the next few days; one will bring severe weather to the South and snow to the North, while the other will bring heavy rain and heavy snow to parts of the Northeast and Canada.

Headlines

  • Heavy rain tomorrow in South Florida.
  • Heavy rain Saturday for the Mid-Atlantic and Northeast.
  • Heavy snow again in the interior Northeast up into portions of eastern Canada this weekend.
  • Heavy snow North and severe weather possible South Sunday-Monday.

An East Coast soaking

There will be two areas to watch in the Eastern U.S. this weekend. The first is in South Florida tomorrow, where heavy, soaking rain will likely fall south of Alligator Alley. For Metro Miami, this probably won’t be a huge ordeal, but there will likely be some areas of street flooding. Southwest of there is where the heaviest rain will occur. Fortunately, it’s a relatively sparsely populated area. Rain will move in toward morning and continue off and on, probably escalating in intensity through the afternoon or evening.

The heaviest rain tomorrow into Saturday morning will be south and west of Miami, where as much as 6 inches or more will occur near Flamingo. (Pivotal Weather)

The second area to watch will be in the Mid-Atlantic and Northeast on Saturday where yet another round of rain is expected. For those of you scoring at home, the Northeast has had quite a bit of rain since last year. So far in 2024, the region is running around 120 to 175 percent of normal rainfall.

Most of the Mid-Atlantic and Northeast have seen above normal rainfall so far in 2024. (High Plains Regional Climate Center)

The ground is pretty saturated heading into spring, and this next round of rain will add anywhere from 1 to 3 inches more to the mix, likely leading to some street flooding in spots. Minor river flooding is also a possibility in a few locations.

Heavy rain on the order to 1 to 3 inches or a bit more is expected from the Mid-Atlantic into Southeast New England, adding to a 2024 surplus. (Pivotal Weather)

There is potential for yet another system later next week in this region as well.

More snow in the Northeast, too!

In addition to the rainfall impacts of this system, heavy snow will be possible for portions of northwest New England and up into eastern Canada, particularly toward the Gaspe Peninsula in Quebec and perhaps northern New Brunswick. For most of Atlantic Canada, this will likely be a rain and gusty wind event.

Major winter storm impacts are likely from interior Maine into portions of New Brunswick into the Gaspe Peninsula of Quebec. (Pivotal Weather)

There are still some things to sort out, but winter’s not done yet here.

As we noted yesterday, winter ain’t over in the Central U.S. either! We continue to see high odds of plowable, significant snowfall for portions of Minnesota, particularly from the Twin Cities south and west.

Significant snow and wind are likely from Minneapolis/St. Paul and points west and southwest. (NWS Twin Cities)

There remain high odds that the Dakotas will also cash in on this one with at least 6 to 12 inches of snow. A wintry mix would be possible on the southern fringe of all this, from Nebraska into southeast South Dakota and perhaps Iowa or southern Minnesota. An impressive, active late March weather pattern.

Severe weather chances Sunday-Monday

We got an update today from the Storm Prediction Center on next week’s severe weather risks in the South. Things are generally unchanged for Sunday in the Southern Plains with an axis of severe storms possible from Kansas through Texas. A new area was highlighted for Monday in the Deep South.

Severe outlooks for Sunday and Monday show a chance for severe storms in the Southern Plains Sunday and the Deep South/Mid-South Monday. (NOAA SPC)

The first day of storms on Sunday will probably initially be some isolated strong to severe storms; where you’d typically see a couple tornadoes try to develop. But that should quickly transition into more of a “linear” type squall line and damaging wind/hail threat. On Monday, with some of the better Gulf moisture in place over the Lower Mississippi Valley, we could see a slightly better chance at severe storms, including supercells and/or a few tornadoes in that area. I think Monday has more risk than Sunday right now to be a more impactful day, but as always, we’ll see.

More severe weather chances may have a chance to emerge later next week, but nothing currently looks concrete in nature.