ATL: NATE - Post Tropical - Discussion

[NDG]

Just as the models forecasted the better UL environment over the NW Caribbean taking over from just 24 hours ago.

[Dean4Storms]

You have to wonder if all that convection to its NE and East isn't keeping the Ridge influence backed down a bit at the surface.

[tolakram]

big swing lol, come on guys it's going to be a sloppy system and rain event with some descent winds..lets hope and pray nothing worse but I think the models have a grasp on the system, I say low cat 1....but models are good 48 hours out.....they have been pretty consistent with the destination the last over the last couple of runs

What model runs are you looking at?

GFS 4 run trend.

[GCANE]

Probability increasing this shoots thru the Yucatan channel and straight over the Loop Current.

[gboudx]

Update from Jeff Lindner:

Hurricane Watch is in effect for the US Gulf coast from Morgan City, LA to the MS/AL border

Tropical Storm Watch is in effect from Morgan City, LA to Intracoastal City, LA and from the MS/AL border to the AL/FL border

Storm surge watch is in effect from Morgan City, LA to the AL/FL border including Lake Pontchartrain.

Nate will accelerate across the NW Caribbean and Gulf today and Saturday and landfall on the US Gulf coast early Sunday

Mandatory evacuations are in effect for portions of SE LA outside of hurricane protection levees

Discussion:
The center of Nate has emerged over the waters of the western Caribbean Sea overnight and recent USAF mission indicates the surface pressure has fallen from around 1000mb to 995mb with surface winds mainly to the east of the center near 45mph. Nate is a tropical cyclone embedded within a large monsoon circulation over central America which is preventing the system from developing rapidly at the moment. A NOAA high altitude mission yesterday evening sampled the air mass surrounding Nate and found an extremely moist profile with deep tropical moisture extending up to the 300mb level. Additionally, a powerful low level jet axis will be developing within the southern flank of the monsoon circulation aimed at the SW Caribbean Sea and into the eastern flank of Nate over the next 24 hours which will help to begin to accelerate the system NNW.

Track:
The rapid acceleration of Nate toward the NNW has begun with the forward motion now up to 14mph. There has been some modest changes to the forecast track guidance in the last 24 hours with several models now showing Nate hooking a harder right or NE turn just before landfall over SE LA. Given the west to east direction of the US Gulf coast a deviation of the motion toward the NE prior to landfall could potentially alter the landfall point. Models also continue to indicate a very fast forward motion of 20-30mph over the Gulf of Mexico as Nate is swung NNW/N on the western flank of a building high off the FL east coast and on the NE side of a strong upper level low over the SC Gulf of Mexico and ahead of an approaching cold front over the central US. Nate should reach the NE Yucatan tonight and then then NC Gulf of Mexico on Saturday afternoon and landfall along the SE LA/MS/AL coast early Sunday morning.

Preparations to protect life and property must be completed today along the Gulf coast as conditions will rapidly deteriorate on Saturday.

Intensity:
Nate is in an overall favorable environment, but the competing forces from the larger monsoon circulation that Nate is within may help to mitigate rapid intensification. USAF mission this morning is not finding very strong winds near the center of Nate suggesting the inner core is weak at the moment, however systems over the western Caribbean Sea do not always need much time to develop and Nate could be near hurricane intensity as it approaches the Yucatan later today. Once in the Gulf of Mexico overall conditions appear to continue to favor intensification, with the exception of the increasing forward speed. Nate will become embedded within a very strong mid level SSE flow across the central Gulf of Mexico and while strong winds are likely across the eastern flank of the system, Nate’s fast forward motion may make it hard for convection and strong winds to wrap around the west side. This could help to throw off the balance needed near the inner core for any sort of rapid deepening in favor of more modest intensification.

NHC brings Nate to a 80mph cate 1 hurricane at the 48 hr forecast point, but Nate could continue to increase in intensity up to landfall around 50-54 hrs from now.

Impacts:

Storm Surge:
Storm surge flooding of 4-6 feet above the ground near the coast will be possible over SE LA including the N/W shores of Lake Pontchratrain eastward along the MS/AL coasts including Mobile Bay. Given the exact track over/near SE LA large portions of SE LA outside hurricane protection systems will be covered in sea water…in some cases to several feet deep.

Storm Surge Inundation Map:
http://www.nhc.noaa.gov/refresh/graphic ... n#contents

Winds:
Tropical storm force winds will arrive into SE LA early afternoon on Saturday and build to hurricane force Saturday night and spread inland over MS/AL/western FL panhandle. Core winds of Nate will landfall over SE LA early Sunday morning and then spread rapidly NE across much of MS/AL on Sunday and well into N GA/TN Sunday night. Large areas of power outages will be possible given that Nate’s wind field will move very far inland.

Rainfall:
Due to the rapid forward motion of Nate rainfall amounts of 5-8 inches will be possible along the track of the system with isolated totals up to 15 inches.

SE TX Impacts:

Moisture will be increasing on the NW flank of Nate across the NW Gulf of Mexico today and tonight. A few outer rain bands may approach the upper TX coastal waters tonight into Saturday and a few of these may move inland along the coast.

Winds will increase out of the ENE/NE into Saturday night with speeds on average of 10-15mph inland, 15-20mph along the coast, and 20-25mph across the waters.

Tides are already running 1-2 feet above normal and this will continue with ENE winds and larger swells moving into the coastal waters on Saturday. Could see values push near 3.0-3.5 feet on Saturday of total water which may cause minor overwash near Hwy 124/87 on Bolivar.

[Frank P]

Strongest winds are well east of the center, and in an area free of convection. Hard to strengthen rapidly without convection over the center. Model trends overnight are just east of New Orleans. Landfall (final) near Gulfport, MS. I would think that Nate would be weakening at landfall, as it will be moving at about 20 mph by then. Could produce a storm surge into Mississippi of 6-7 ft. That's enough to wash over Hwy 90 between Biloxi and Gulfport.

A surge of 7 feet would not even reach the base of the sea wall at my house.... takes at least 8 feet to reach the base and 10.5 feet to breach the top of the sea wall... other areas of 90, especially around restaurant row near Veterans Ave and the casinos down in east Biloxi this would overflow 90 and cause some problems... Gulfport's low point is at the 90 Cowen road intersection and points westward... which is pretty low and would be covered...

[SEASON_CANCELED]

Looking at anywhere from Tropical storm to Cat 2.


Katrina was a Cat 2/3 at landfall..no?

[Dean4Storms]

I've got a big Class A RV on a lot I own about 2 blocks from the Gulf. Thinking I might better get it out of here tomorrow seeing this east shift.

[Jag95]

Anyone else find it strange that NHC has landfall a little west of Pascagoula, MS but only has a Hurricane Warning in effect to the MS/AL border? Last night I thought this meant they were anticipating more westward shifts in the track, but this morning the track is a little farther east.

Yes, I was thinking the warning area is a little tight on the eastern side. I would bet they'll expand it fairly soon.

[Kazmit]

Looking at anywhere from Tropical storm to Cat 2.


Katrina was a Cat 2/3 at landfall..no?

Katrina was a high-end Cat 3 when it made landfall. I doubt Nate will get that strong, however.

[CrazyC83]

I do expect they will expand the Hurricane Watch (or Warning) well to the east, probably including Mobile and Pensacola. I'm thinking the Hurricane Warning will end at the mouth of the Mississippi River (and does not include NOLA metro, which would be under a cane watch and TS warning).

My guess at the 10 am advisory:

Hurricane Warning - Mouth of the MS River to Okaloosa/Walton County Line
Hurricane Watch - Morgan City to the mouth of the MS River, including NOLA and Pontchartrain
Tropical Storm Warning - Morgan City to the mouth of the MS River including NOLA and Pontchartrain; Okaloosa/Walton County Line to Panama City
Tropical Storm Watch - Intracoastal City to Morgan City (wait a bit longer before dropping that)

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

[Dean4Storms]

Recon is finding the highest winds well east of the center, something also to note!

[nativefloridian]

[quote="NDG"]LLC almost free of deep convection near it, though a few storms are starting to form just to the east of it, still moving fast, as if it decoupled from the mid level vorticity last night.



I agree with your comment. To my untrained eye it appears the LLC is racing ahead a bit north and east of the official NHC track.

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

[caneman]

If it stays looking like that some of the heaviest rain could be along the west coast of Florida

[NDG]

Nate is doing exactly what last night's Euro forecasted.

[Blown Away]

12z Intensity Guidance... Trending down... Modest TS per the guidance up to NGOM coast...

[FLpanhandle91]

In the famous words of tolakram, let's keep the focus on the models here people.

[GCANE]

[tolakram]

Visible loops.

COD: http://weather.cod.edu/satrad/exper/?parms=meso2-02-96-1-100

SLIDER: http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=mesoscale_02&x=1007.5&y=1036&z=2&im=18&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

[NDG]

Based on the distance and timing between the 2 VDMs from the recon, Nate moved at an average speed of 18.8 mph!!!