vortex95

IMHO, I think they are really pushing the limit for HU watch here. Yes, the pressure is down, but the convective area waned considerably at the time until about an hor ago, yet NHC did not even acknowledge this clear cycle down on sat? Again, I think they tend to not include if they can anything that show weaker or a struggle, but as posts noted on the thread in the last few hours, Edouard looks not so good (skeletal). So I am just speaking out loud here what others might be thinking as well and not thinking in an isolated vacuum! Yes, the risk is there, but err'ing on the side of caution I find influence more by social pressure rather than sticking to the met science these days, which has advanced big time over the decades. And, yes, I am aware of what HU Humberto did in Sep 2007 in the very same area, but that was an exceptional event, no other like that on record, so that alone is not enough. Also objectively, current environmental conditions concerning dry air are a sig problem as evidenced by the wane of convection earlier and what we see just to the N on the mid-level WV, so that would count against such aggressive RI. All I am saying is that the door swings both ways here, so in Edouard's case given the factors, IMHO would be more logical/practical to split it down the middle (steady but more modest straightening). rather than chose any one clear direction until we actually see evidence of RI. esp on satellite/radar and it being in a data rich area. It's not like we will be in the dark as to trends hour-by-hour. Lots of platform sfc obs off the LA coast, as one example. I know I am verbose and sound pedantic, but it shows how there is a *lot* to consider in TC forecasting, and forecasting in general. How one chose to go in any given situation is subjective of course. My position is that I do not go high aggressive in a forecast until I see clear reason to do so ((in other words, not forecast an outlier, rare, or exceptional event unless it is clear it has a good chance of occuring), and the amount of wx data and its detail these days, one can afford to "wait and see" more IMHO.

Some get *far* to impressed w/ large MCS areas w/ very cold cold tops for nascent TCs. Yes it is intense convection, but that does not correlate well when it blows up very fast b/c that often mean it will dissipate just as fast. And the collapsing convection hinders organization at low-levels, .It can also happen when a system of mdt TS status. You get this immense area of very cold cloud tops, sometimes below -100 C, in a rather symmetric blob, calked a CCC, but there is no banding. When this happens, the TC often is stunted in intensification until the CCC feature goes away. If Edouard has a blow up of convection overnight, watch closely, Does it form in a coherent band as we are seeing on the N side now, or is is just random blobs (zits!) expanding radially? Also, you can have a combo of this. Banding now on the N side is good, but nothing on the S side, This implies dry air wrapping in. Also, the banding on the N side may be due to frictional convergence from the LA coast. Still, that can increase max winds b/c the stronger convection mixed down higher winds aloft better and the band is pushing against weak high pressure to the NE

As hurting as the convection is, at least it is nicely circularly-banded and looks more like a classic TC. Did not have that at all w/ Arthur, Bertha, Cristobal, or Dolly. Shear was the big issue for those. Edouard's issue is dry air, but you can do a bit better overall for max TC intensity when only dry air is an issue I have noticed empirically.

Yes, NW flow events are *notorious* in New England for its biggest tor events and outbreaks. Historically, it is a little less defined in the Mid-Atlantic b/c it does well in SW flow (College Park, Sep 2001) and TC events (remains of Ivan in Sep 2004), but you have June 23, 1944 (WV hit hard) and June 2, 1998 (Frostburg MD F4). https://www.weather.gov/lwx/events_19980602 https://www.tornadotalk.com/june-2-1998-tornado-outbreak/ And, of course, the derecho on June 29, 2012. I think an EML present is important for high-end derechos.

I have only lived in the DC area for 8 years, and I am still trying to get an overall feel for local nuances when it comes to tstms, esp. when the "DC split" occurs. That seems more than just a random coincidence. And it is apparent the corridor from about 30 mi W of BWI to the city is a favorable area, so is just E of I95 to the Delmarva, and it seems really apparent CHO-RIC-ORF area in terms of a "hot spot!" Also, w-cntrl and swrn VA get some really nicely-structured supercells at times!

"Boring?" Good to see you post elsewhere, not just always on the Weymouth MA...er, I mean New England forum!

Tiny sucker!

1010 mb for a c.p. is pushing it for TS-intensity objectively, but Edouard's small size means a tighter gradient hence stronger winds than you would normally expect. Andrew N of PR in Aug 1992 when it was struggling against against an upper level low has a 1015 mb pressure per recon and they still found near hurricane-force winds at FL!, so they kept it at a 40 kt TS, but one could argue it opened up as a trough for a time. You can see dry air entrainment is still an issue (SHIPS diagnoses 700-500 RH of 48% -- anything less than 60% is not good) w/ a sig waning of the deep convection in the last several hours. I am not sure why NHC does not explicitly mention dry air as a mitigating factor. Sure the shear is low and SSTs high, but you need all three solid/favorable for steady intensification or RI. We saw this w/ Lala. They kept saying "conditions generally favorable" repeatedly w/o going into the individual factors, such as dry air to the N and NW w/ a stable stratocumulus field. Yes, Lala intensified, but only slowly. My point is we can do better for details when diagnosing and pronosticaing a TC. Sometimes I think they hedge slightly to avoid anything that makes a system less of a threat on a perception level. I say, tell it like it is in detail objectivity based on the met science alone, no bias either way! And ppl (esp. wx weenies!) want such details I have found since it is not "one-size fits all" for TCs. That's how everyone learns! The finer points and details on wx phenomena that are not immediately apparent or well-known I find the most interesting.

I don't know, Many times in WNW or NW flow, mountains to the W do well, then is often a gap due to downslope flow between IAD and DCA, and then it picks up again due to the bay breeze and higher dew points E of I95, But its not easy tell on any given days the "DC split" occurs, and w/ an EML present, that makes it more complex b/c nighttime convection is more common and often not surface-based, so downslope flow is not as much of a factor.

Four days in a row svr risk in this area, esp. this time of year? Sure ,lots of days get upgraded to slight risk the day of and we get 4 days in a row of svr risk, but to have days 3, 4, and 5 outlooked means synoptically it is defined and impressive, which means higher-end svr wx possible. Usually in this part of the country, you don't get multiple days in a row w/ svr wx from NW or WNW flow b/c one wave of convection and it s/w trof clears things for moisture, and it takes a bit of time to recover. Or the front/boundary gets pushed farther and farther S w/ each wave of convection. But the way the mid and upper level ridge is during this period looks like it may force things to be in the same general area repeatedly. Why not? Every so often things do work out for relentless stormy wx in a region! One might say, "4 days in a row, *everyone* should cash in and get crushed at least once during the period!" I hope so. W/ an EML present, you can do some nice things during the overnight hours, esp. with crazy LTG.

Invest 97L -- if this system makes TS-strength, it is likely to be among the smallest TCs on record. Compare the WV image of 97L currently to an image of Macro from Oct 2008 in the Bay of Campeche, which is the smallest TC on record (both attached). The small size is a product of how unfavorable conditions are in the Atlantic overall for TCs. Yes, in the Gulf the shear is low (unlike the MDR) but mid-level dry air is an issue. Nary any other convection in anywhere near 97L! @CoastalWx will say, "still does not break the BORING pattern!!!" But wx always has something KEWL going on if you do not confine yourself w/in 5 mi of Weymouth!

Also, 97L is *tiny*. In fact, it is not that much larger in convective coverage now than smallest TC on record -- Macro in Oct 2008 in the Bay of Campeche. I attached a current WV of 97L and image of Marco. The small size is a product of how unfavorable conditions are in the Atlantic overall for TCs. Yes, in the Gulf, the shear is low (unlike the MDR) but mid-level dry air is an issue. Nary any other convection in anywhere near 97L!

I think they are holding off on PTC b/c it is not clear it will be a TS before landfall. They do not want to put up TS warnings due to this uncertainty b/c of the impact alone warnings have. It puts things different level from a EM standpoint and business/commerce. 97L looks better on sat and radar as I type this. Will they declare it a TD or do PTC by 5am?

The sensible wx impacts from a strong tropical wave can be just like minimal tropical storm. That's the challenge faced by NHC and other wx services at times b/c the public mostly cares about/sees the impacts, not scientific definitions. But we can't just arbitrarily call something this or that b/c it has wx that appears mimic something else! A typical baroclinic cold core low pressure over the open ocean, many easily have winds of a Cat 1-2 hurricane, and pressures below 920 mb in extreme cases, and overall power as much as a Cat 5, just the wind energy is spread out over a much larger area

The convection is still strongly pulsing, and NHC likes to wait to see more persistent and coherent convection or decent circular banding before declaring a TC, which is a good mode IMHO. Quickly waxing/waning convection is a sign of dry air or shear, and pulsing the convection results in cool outflow boundaries that interfere w/ the organization of the LLCC. It is also a very small system, and small systems are more susceptible to environmental factors. In this case, lots of dry air just to the N that can get entrained easily. Looking at the 00z SHIPS output for 97L here, you can see the 700-500 RH is quite low. (below 50%). https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al972026/stext/26083100AL9726_ships.txt