ATL: HARVEY - Post-Tropical - Discussion

[psyclone]

Most state rainfall records in the gulf coast region are a result of tropical systems that got stuck in a weak steering regime...the potential here is very serious from a freshwater flood standpoint and folks should contemplate the possibility of a very high impact event and plan accordingly.

[Steve]

good luck all in Texas

I'm in corpus and I'm prepared for anything so is our city we actually have a meeting in downtown at 6PM discussing what we are gonna do !!!

Drink. And pour another one.

[Tireman4]

I'm getting tired of this storm.

No biking this weekend? It's payback for your many years of taunting Portastorm during the winter months!

Seriously, good luck to you Wxman57 and everyone else down on the coast. Y'all are in my thoughts and prayers.

Yeah...the taunting...the laughing....the out right sneering at us...the bi polar forecasts..gracious...yeah...this could be bad. All make sure to heed the warnings..

[Steve]

Sorry if this has already been asked. 70+ pages!
How will Harvey's stationary time in the gulf affect his track once he does get going? Would more time stalled cause him to move more north as opposed to NW? More west? What factors will affect his steering?

I thought I knew but I don't now. There was an ULL to the NW of Harvey which has grown weaker. There is a high coming across the central US soon and I think an upper low after that. There is also ridging for the moment in the SW Us pushing against anything getting too far west unless it's really far south. That's all got to play out. Most of the models have gotten somewhat similar (factoring in known biases) with an approach to the TX Coast. There is divergence after that. So different models are looking at other environmental factors differently.

Best recommendation is to pull up a Satellite of the US or North America and see what shows up. Then run the models you want to look at at 500mb. That level usually catches large scale weather pattern features such as highs and lows. It's at about roughly 3.4 miles up (halfway up to jet flight level) vs 850 which is slightly less than a mile or the surface which is at the surface.

[GCANE]

Can pretty much say good bye to that ULL.

[Hurricaneman]

Looks like outer bands in Louisiana, quite the large system

[storm_in_a_teacup]

Lightning in a TC can indicate either dry air in the core or that it is organizing and producing some deep convection. I would say it is probably due to a little dry air being mixed out and the recent explosion of deep convection.

That seems to be the case.

Out of curiosity what is the reasoning behind dry air ingestion and increased lightning? Increased cooling/destabilization of the mid-upper lvl profile due to evaporative cooling/sublimation resulting in increased updraft strength?

Yeah I'd really like to know the answer to this as well. Is anyone willing to give it a shot?

[stormreader]

Storm system becoming more expansive, but smaller inner core looking better too. Starting to look like the real deal.

[Hurricaneman]

Lightning in a TC can indicate either dry air in the core or that it is organizing and producing some deep convection. I would say it is probably due to a little dry air being mixed out and the recent explosion of deep convection.

There was an ULL giving some dry air to this system and can lead to strong convection leading to having lightning
That seems to be the case.

Out of curiosity what is the reasoning behind dry air ingestion and increased lightning? Increased cooling/destabilization of the mid-upper lvl profile due to evaporative cooling/sublimation resulting in increased updraft strength?

Yeah I'd really like to know the answer to this as well. Is anyone willing to give it a shot?

Dry air from the ULL causing that and the ULL seems to be gone

[xironman]

Bye-bye pressure

[SuperMarioBros99thx]

I think due to warm SSTs along Harvey's path Harvey could go to RI. Think of Hurricane Bret in 1999. This could be much more of disaster than Bret itself.

[storm_in_a_teacup]

There was an ULL giving some dry air to this system and can lead to strong convection leading to having lightning
That seems to be the case.

Out of curiosity what is the reasoning behind dry air ingestion and increased lightning? Increased cooling/destabilization of the mid-upper lvl profile due to evaporative cooling/sublimation resulting in increased updraft strength?

Yeah I'd really like to know the answer to this as well. Is anyone willing to give it a shot?

Dry air from the ULL causing that and the ULL seems to be gone

I meant in general how dry air could cause lightning. I have never heard this before, only that lightning sometimes happens during rapid intensification.

[tarheelprogrammer]

Good luck to the NHC, and the other experts. This storm is going to be hard to predict up till landfall, and then after it as well.

[South Texas Storms]

Based on the latest GOES-16 visible satellite loop, it looks like Harvey has been tracking slowly northwestward over the past few hours.

[txwatcher91]

Yeah I'd really like to know the answer to this as well. Is anyone willing to give it a shot?

Dry air from the ULL causing that and the ULL seems to be gone

I meant in general how dry air could cause lightning. I have never heard this before, only that lightning sometimes happens during rapid intensification.

I’m not entirely sure the physics behind it, but I believe it’s similar to how static electricity builds up easier on a dry winter day vs warmer, moist air. Maybe one of the pros can explain it but that’s my basic understanding of it.

[tatertawt24]

Yikes, it hasn't even reformed into a TS yet and states of emergencies have already been declared? How often does that happen?

[Dean4Storms]

Based on the latest GOES-16 visible satellite loop, it looks like Harvey has been tracking slowly northwestward over the past few hours.

Agree and maybe even NNW and looks tilted from NW(surface) to SE(mid-level). Sheared a bit.

[RL3AO]

Yikes, it hasn't even reformed into a TS yet and states of emergencies have already been declared? How often does that happen?

More frequent in recent years. States and counties are getting smarter and trying to prepare and place resources well before the storm impacts an area.

[jasons2k]

Some info on lightning:

http://www.aoml.noaa.gov/hrd/tcfaq/G9.html

[tarheelprogrammer]

Quick question for any of the pro METS on here. How is this not a TS? I have personally seen much worse from recently named TSs.