Tracking the Tropics: Milton Quickly Intensifies to a Hurricane

Recent recon early Sunday afternoon has shown Milton now has 80mph surface winds, which is enough evidence to upgrade to Hurricane Milton in the intermediate advisory:

I wanted to cover some of the steering influences that will dictate where Milton is heading. First, let's take a look at our major synoptic steering flow (and why this is heading towards Florida). This is an excellent product/cmap recipe from Alex Boreham (FSU grad) and Deelan Jariwala. I've outlined here our stalled out front just north of Milton (pink), as well as the high pressure features over CONUS (yellow). This setup has caused a near ideal environment for Milton, and steering has been rather lax (hence the southward drifting and positional correction). At the very top of the map, I've outlined in green our cutoff trough that is starting to dig towards the SE. This will break down the ridging (dashed yellow) and allow Milton to eventually move northeastward more quickly in the forecast period:

That's our general alleyway for track from a synoptic point of view, but what about nuances/deviations in timing? This is important, as we just saw with Helene. Let's take a loot at two polarizing deterministic runs from the 12z suite, a much slower CMC run that is further south and a much quicker run with the GFS. Let's look at a snapshot at 42 hours first of MSLP, as there are some important details to point here. First, the GFS has a significantly stronger system than the CMC. Also, our cutoff low on the GFS run is much deeper (MSLP) than the CMC:

Another factor that is important, how Leslie will modulate ridging to the east of Milton. If we go out to 72 hours, we have DRASTICALLY different solutions now in the deterministic runs. The GFS is already closing in on landfall, while the CMC solution is still stuck around the Yucatan peninsula. Why is this? Let's timestep to 54 hours, and look at the difference in our 588 DAM line. Leslie has eroded the ridging to the east, and this allows our cutoff trough to the northeast to have more of an influence (the GFS also has a deeper system, so the upper-level flow from the cutoff low/troughing has more of an influence):

Which model has the more correct solution? If we look at 500mb verification scores for CONUS (which helps us see which model is handling our troughing/ridging the best), the GFS has been playing some catch up here:

If we also look at verification biases of the global deterministic models, there is a noticeable left of track bias in the GFS (you can check out verification scores here - https://www.emc.ncep.noaa.gov/users/ver ... _cyclones/). Let's take a look at Helene for an example (another situation with a cutoff low, but different geographical location). Our GFS was again left of track for verification:

So is the GFS solution worthless? No, because it actually is our best performing model when it comes to intensity (which we can see with Leslie, is important here), we just need to know its biases and correct for those:

The best solution here (and the one the NHC will not deviate far from) is to use a consensus blend of models that correct for these biases. One of the best models for this is the TVCN, and we can see the trend for the TVCN has been shifting southward. I do expect some more shifts (this could be more northerly or southerly, or the windshield wiper effect as we call it) as the models lock in more on the upper level features but I do think just north of Tampa down to Sarasota is becoming an increasingly likely landfall location:

-- Matthew Weiberg