jconsor

The remnants of Ian are becoming a hybrid low near the mid-Atlantic coast with a shallow warm core (mainly 850 mb and above). The interaction between this very slow-moving low and a strong high pressure system over E Canada and the NE US is creating a major, multi-tidal cycle coastal flooding event from northeast NC to southern NJ that will continue into Wed.

The remnants of Ian are becoming a hybrid low near the mid-Atlantic coast with a shallow warm core (mainly 850 mb and above). The interaction between this very slow-moving low and a strong high pressure system over E Canada and the NE US is creating a major, multi-tidal cycle coastal flooding event from northeast NC to southern NJ that will continue into Wed.

The remnants of Ian are becoming a hybrid low near the mid-Atlantic coast with a shallow warm core (mainly 850 mb and above). The interaction between this very slow-moving low and a strong high pressure system over E Canada and the NE US is creating a major, multi-tidal cycle coastal flooding event from northeast NC to southern NJ that will continue into Wed.

How much troughiness is left in the E. US after day 10 may play a role if this possible TC slows down and hangs around long enough in the W. Caribbean or over C. America.

I'd recommend being wary of GEFS members showing a potential path northward for the system entering the Caribbean middle of this week. IMHO, *if* it fails to become a TS with a well-defined circulation before the latitude of the Dominican Republic (~70W), it looks most likely to be a straight W/WNW tracker like the Tampico Hurricane in 1933, Janet in 1954, Joan in 1988 and Iris in 2001, heading into Central America or southern Mexico. However, if it manages to develop sooner, especially on approach to the Windward Islands, the picture becomes much more complicated.

I know this is not what residents in the Greater Antilles and along the Southeast US coast want to hear after Fiona and Ian respectively dealt them a severe blow, but looks to me that early Oct will be quite active, and not just in the usual W. Caribbean hurricane breeding grounds for this time of year.

Thread on severe inland flooding in central Florida in the Orlando-Kissimmee metro area. That area contains hundreds of small lakes, basically a sitting duck for flooding when heavy rains hit. However, this flooding is clearly historic! A thread of videos and photos of the inland flooding in central FL:

Ian's western eyewall appears to be nearly as strong as the eastern eyewall! Here are Andy and my explanations for why this may be the case. Hurricanes Michael and Delta saw a similar pattern.

Very interesting, @turtlehurricane! Do you have any published papers (either by yourself or others) that you can share on the topic you mentioned - frictional convergence near the coast feeding high vorticity into the eyewall and amplifying the vortex? Thanks. A quick Google scholar search yielded two papers from the 1990s, one on Hurricane Andrew and one on Irene which hit S FL in 1999: https://journals.ametsoc.org/view/journals/bams/77/3/1520-0477_1996_077_0543_haifdo_2_0_co_2.xml https://www.iweathernet.com/print/irene-1999.pdf (Easier to read version at https://www.iweathernet.com/tropical/hurricane-irene-1999-intensification-and-downbursts-after-landfall) Here is a more recent one I found: https://www.sciencedirect.com/science/article/pii/S2225603219300499

There are several analog hurricanes which hit SW FL from the S/SSW. The most similar ones are Charley and especially the infamous Oct 1944 Cuba-Florida hurricane. The Oct 1944 storm was similar in size to Ian and much larger than Charley, and hit as a category 3 with pressure of 949 mb. The similarity of the Oct 1944 hurricane to Ian is quite concerning for the insurance industry in FL, which is already reeling from the recent loss of numerous insurance providers. If the Oct 1944 'cane were to hit today it be expected to cause direct economic losses (damage) of around $80 billion - adjusting for per-capita wealth and population increases as well inflation! See the tweet below for methodology for calculating normalized losses from past hurricanes.

Great point here by Brian. Though Ian's intensity and track leading up to landfall is very similar to Charley, Ian is much larger than Charley! This will lead to a higher storm surge and much larger area impacted by destructive storm surge and winds.

Update on the expected pressure pattern for Aug and resultant SST trends for the MDR.

Counterpoint to some recent discussions about anomalously dry air in MDR persisting into mid-August. Looks to me like significant changes are afoot, with a moister MDR expected beginning in about 7-10 days. Given the improved upper level pattern/reduced shear as well as gradual moistening of the MDR, I would expect a TC to form in the MDR by the third week of Aug, perhaps a day or two earlier.

Thread on SST evolution and analogs:

Thread on two stronger than expected tropical waves in the eastern Atlantic.

Thread on potential heavy rain event mid to late next week for portions of the mid-Atlantic and northeast. The heavy rain threat would exist in any case due to a slow-moving, deepening eastern US trough. However, the heavy rain risk could be amplified due to interaction between the trough and a slow-moving system forming near the central Gulf coast by Mon, which could be slingshotted NE and become a hybrid system.

Be careful with CDAS. It is known to significantly underestimate Atlantic SSTs, especially in times of strong SAL. Also from experience I recommend being careful with NCEP/NCAR reanalysis-based SST. It runs much cooler than most other datasets. OISST and HADISST are better choices. Also keep in mind there was significant warming in the MDR in the last two weeks of Jun. After some brief cooling in the next week or so with a surge of stronger trade winds in the MDR, weaker than normal trade winds are expected to return second half of Jul into early Aug per long-range EPS and the weekly EPS. This would likely lead to further warming by the peak of hurricane season. This is consistent with stronger than usual West African Monsoon that has prevailed since 2015, contributing to reduced trades and helping to warm the MDR between Jun and Sep. I like the idea you came up with, of comparing this La Nina with the past 10. On the ESRL site, OISST and HADISST are not yet updated for Jun. When they update, I would be interested to see your plot would appear with those datasets.

Thread on the "missing" warmth in the eastern subtropical Atlantic (part of the +AMO tripole signature) and why it is expected to return in mid to late Jul.

GFS has been better than the ECMWF in terms of showing the area of concentrated deep convection N. of Panama (and the convection in the SW Caribbean in general). It is still likely too quick to show development and intensification, but something in between the GFS/GEFS and ECMWF/EPS is possible IMHO.