Saturday, November 7, 2009

IDA nears Hurricane Strength...

Hurricane Hunters have found max winds in IDA now at 70 mph. She will become a Cat. 1 later this afternoon. Where will she go? What we do know is IDA will enter the southern Gulf before dark on Sunday. What we do know is the farther north she goes, the cooler the waters get. What we do know is the farther north she goes, the stronger the wind shear over her. Translation...Ida will not maintain her hurricane strength as she moves closer to us.

Now the complicating factors. 1) there is another large swirl of low pressure (non-tropical cold core) clearly visible on sat. loops over the SW Gulf. 2) an upper disturbance approaching the Gulf from Texas should pick up this low and head it to the NE tomorrow. 3) This upper disturbance should pull Ida into it on Sunday.

Questions. 1) As Ida weakens on Sunday, will she become more non-tropical and be like a winter time system? 2) How will that influence her future track?

If you have followed me over the years you know I don't get concerned until a tropical system gets into the Gulf. IF this were August or September, yes we all should be worried, But we are in November and 1) there is lots of cool, dry air over the northern Gulf and water temperatures are much cooler than back in the summer and upper level winds are forecast to be 30-50 kts over the Gulf so, at worst what's left of IDA will bring us some gusty winds Monday (20-30+) along with some heavy downpours (1-3" in LA, 2-4" in MS). Gustav showed us our levees protect us up to a Cat. 2 storm very well. This will not be a Gustav, but it will be a good test to see what the new rock dam on the MRGO does to water levels. VIPIR flipped flopped on last nite's model run. Let see what tonight's run shows. We need to see consistency in runs to have any confidence in the forecast. Next update late tonight after 10 PM.

2 comments:

ONLYREAL said...

Enjoy the beautiful weather while it lasts today because it will abruptly come to an end on Monday. With the Global Computer models finally in agreement I can finally say with confidence that the weather could get quite rough early next week. Today expect mostly sunny skies with some high Cirrus clouds and maybe some cumulus clouds this afternoon. Highs should rise into the Upper-70's with winds out of the East at 5-10mph. Sunday you will notice increasing cloudiness throughout the day and that the winds will be picking up a bit from the East. Showers should hopefully hold off until Sunday Night.

This is where things get complicated so bear with me... On Monday Tropical Storm Ida(Could very well be Hurricane Ida) will enter the Southern Gulf of Mexico and will encounter strong westerly wind shear and this will cause the Tropical Cyclone to transition to an Extra-Tropical Cyclone, which means instead of the strongest winds being near the core the strongest winds will be experienced far from the center. Meanwhile, there will be another Extra-Tropical Low Pressure system developing in the Bay of Campeche. Also there will be an approaching cold front (trough) which will cause both systems to move Northward. Once Ida has has made the full transition to Extra-Tropical Cyclone status the two systems will merge with each other and become one large Extra-Tropical Tropical Cyclone just off the SE Louisiana coastline Tuesday evening. With an area of High Pressure to the North of the large cyclone, this will induce a strong pressure gradient to develop which means there will an area of rather strong winds on the northern side of the system. The winds on Tuesday night are currently forecasted to be out of the East at 20-30mph with gusts to 50mph possible so you may need to secure loose objects on your property in case current forecasts verify. These strong Easterly winds should also cause some coastal flooding. Winds will then shift the the North then North-East by Wednesday morning. Up to 3-5 inches of Rain(locally higher) is also possible with this system, and this raises the concern of street flooding so hopefully it will fall over an extended period of time. Finally the cold front will move through by Wednesday putting an end to most of the rain though a lingering shower or two will be possible with skies clearing by Wednesday Evening.

ONLYREAL

ONLYREAL said...

"If you have followed me over the years you know I don't get concerned until a tropical system gets into the Gulf."

Bob,

That is why I have a ton of respect for you. You stay calm until a threat is immanent. You don't hype things that are 5 days out when there is lots of uncertainty like some other people do.

Thanks Bob,

Dylan