WxWatcher007

https://twitter.com/philklotzbach/status/1692220172457971992?s=46&t=Nn9Cx92_8118fPdhHPdJHw

Year’s worth of rain in 24-48 hours in the dry areas would cause some trouble.

Explicitly forecast to be a TS over southern CA. Obviously there’s novelty to that but the rainfall impacts could be bad. Especially with a further west track that brings heavier rain toward the population centers at the coast IMO. Hurricane Hilary Discussion Number 5 NWS National Hurricane Center Miami FL EP092023 900 AM MDT Thu Aug 17 2023 Hilary has continued to intensify rapidly. The cloud pattern of this large hurricane is very impressive, with extremely intense deep convection and cloud tops to -80 deg C or colder. Well-defined banding features are evident over all quadrants of the circulation. The upper-level outflow pattern is quite symmetric and expanding. Satellite intensity estimates are wide-ranging and the Dvorak technique rules do not allow subjective current intensity estimates much above 65-70 kt. However based on data T-numbers the advisory intensity is set, perhaps conservatively, to 75 kt. The hurricane is moving west-northwestward, or about 300/12 kt. Over the next few days, a mid-level ridge to the north of Hilary is forecast to shift eastward while a mid-level low remains near the California coast. This evolution of the steering currents should result in a gradual turn toward the north in a couple of days, which would bring Hilary near the Baja California peninsula in 72 hours or so and near the U.S./California border in 3-4 days. The official forecast track is very similar to the previous one, and follows the HFIP corrected consensus, HCCA, guidance. Although there is fairly high confidence in the track prediction, Hilary's oblique angle of approach to the west coast of the Baja California peninsula makes it nearly impossible to know at this point if the center will remain just offshore or move over the peninsula before reaching the southwestern United States. Hilary is in an environment of low shear and high mid- to low-level humidity, and over very warm waters. The SHIPS rapid intensification (RI) indices show extremely high probabilities of rapid intensification during the next day or so. Therefore the official intensity forecast shows a 40-kt increase over the next 24 hours. Later in the forecast period, cooler waters and land interaction should result in some weakening. The official wind speed forecast is near or a little above the latest HCCA guidance. The surface circulation is likely to be dissipated by day 5, but a day 5 forecast point (as a remnant low) is still provided to maintain a forecast track over southern California. KEY MESSAGES: 1. Heavy rainfall associated with Hilary may produce areas of flash flooding and result in landslides over portions of Baja California Peninsula from late Friday into late Sunday. Rainfall impacts from Hilary within the Southwestern United States are expected to peak this weekend into Monday. Flash, urban, and arroyo flooding, is possible with the potential for significant impacts. 2. Hilary has the potential to bring significant impacts to the Baja California Peninsula and portions of the southwestern United States this weekend and early next week, including after it becomes post-tropical. Although it is too soon to determine the location and magnitude of wind impacts, interests in these areas should monitor the progress of Hilary and updates to the forecast. Tropical Storm Warnings and Watches are now in effect for southern portions of Baja California Sur, and additional watches or warnings will likely be required later today. 3. Large swells from Hilary will spread northward along the coast of southwestern Mexico and the Baja California Peninsula during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 15.5N 107.8W 75 KT 85 MPH 12H 18/0000Z 16.4N 109.4W 100 KT 115 MPH 24H 18/1200Z 17.6N 111.2W 115 KT 130 MPH 36H 19/0000Z 19.3N 112.7W 120 KT 140 MPH 48H 19/1200Z 21.2N 113.7W 115 KT 130 MPH 60H 20/0000Z 23.6N 114.4W 105 KT 120 MPH 72H 20/1200Z 26.6N 115.0W 85 KT 100 MPH 96H 21/1200Z 33.4N 116.8W 50 KT 60 MPH...INLAND 120H 22/1200Z 41.0N 119.0W 25 KT 30 MPH...POST-TROP/INLAND $$ Forecaster Pasch

First tropical landfall this year may be in California lol

Crabgrass is awful

Given the persistent troughing, I do think when we get something recurving off the EC in September or whatever there could be higher than normal chances of a PRE somewhere.

Yeah, the position and amplitude matter. We have some middling features out in the basin now but I think the highest potential comes late month if we can get a CAG in the western Caribbean. That’d bring something north off the SE coast or into the Gulf—if the activity doesn’t center in the EPAC.

One of the benchmark floods (still can’t get these to auto populate) https://x.com/nwsboston/status/1692144247342813547?s=46&t=Nn9Cx92_8118fPdhHPdJHw

I think it will. More concerned about the number of TUTTs and shear that will enter the basin.

Good stuff—points well taken. I agree about the TUTTs that look poised to pepper the Atlantic and the subsidence in the MDR are an issue. For that reason I do think eastern/central MDR stuff will struggle, though not as much as before. Perhaps we get one of those three areas along the MT named? Two if there’s enough separation? Nothing spectacular. I’m honestly more intrigued by prospects further west. Like a number of recent seasons, with a hostile MDR we’ve seen some AEWs find a window in the western Atlantic or Gulf for development. Away from the influence of SAL/Subsidence and maybe (?) a gauntlet of TUTTs we get something to pop—like you said though, that’ll require patience. A strong wave will need to survive the trek, and an August CAG is always low probability and even if one develops, the activity could focus in the EPAC. I continue to believe these next two weeks are critical to the overall season. Unlike prior seasons where an active September and even October provided a backloaded season, if the basin underperforms during this late August period, it becomes extremely hard to see even a normal season (particularly in the H/MH spaces) given the atmospheric response we’re seeing to the niño. I guess that’s a long winded way to say I’m not as bearish as you, but I’ve got my eyes on the towel in case I need to reach for it.

Not sure why the two oranges have the same development odds but only one is an invest. Still need to see development of course but it looks like the switch is flipping on with the monsoon trough breaking down into three areas of vorticity, the potential Gulf development, and what looks like a potential quasi-CAG in the western Atlantic/Caribbean. The GFS has a bunch of weenie solutions with that, but that may have the highest end potential long term for a strong system.

GFS led the way on it too…

Sounds like New England

This is why I keep coming back. Congratulations and best of luck.

Two oranges in the MDR and the lemon in the Gulf now.

I think a 0/20 makes sense for the Gulf. Again, it's not that there's anything particularly special right now with the wave, but that there should be a window for gradual development if it can get stay coherent and take advantage of cyclonic flow in the western Atlantic. It's not surprising IMO that the guidance has a marginal signal thus far, and that they've become more bullish as the wave traverses west.

Gradually coming to life...

I honestly think I’d put a D7 lemon on whatever meanders into the Gulf. GFS has something close to a TC but more importantly, the ensemble signal has grown steadily as we get closer to what looks like a conducive environment for gradual development taking shape.

That wave near the Antilles is worth watching. It may not look like much now as it’s consumed by SAL, or show up as clearly in the Gulf on model runs, but the environment in the Gulf a few days from now look good for something discrete to gain vorticity and organize some.

https://x.com/nwsboston/status/1691419471540318209?s=46&t=Nn9Cx92_8118fPdhHPdJHw

Just to Portland. Just over 3 hours. Long day though.

GFS shifted the stripe of heaviest precip north

The sky was really nice today. Drove up to Maine and back today. Beautiful day.

I’ve tried that and it doesn’t work. Just started happening to me a few days ago. Paging @dendrite

I can’t get mine to auto populate now. Are you doing anything special to get your tweets to do so?