Tropical Storm Nate

[Iceberg]

Well we have Nate.

Recon have gone in and found a closed circulation with 45kt winds so Nate is initiated as a 40kt tropical storm.

This has formed from invest 96L.

It has 3 ways it might go, north which has little support, south in which case it quite quickly disappears. or west which is favoured by GFS and ECM.

It might well depending on Track go onto a hurricane.

[Paranoid]

Two tropical storms in one day? My, we are blessed today. Not sure about the prospects of this storm (not really helped by the fact that the models can't decide which way Nate will be going). The drought in Texas (and a lot of the US) means there's a lot of dry air around the north of the GOM which will probably hamper development if Nate decides to head north, plus shear is around 30kts there.

[summer blizzard]

it should go north given that the west and south solutions were based on a weaker system. should be slow moving and there is a good chance that it will become a hurricane.

[Paranoid]

If it's going to be a slow storm, a Hurricane can't be ruled out (shear and dry air are only high around the coasts, and the shear may be due to the remnants of TS Lee so that'll continue to move north). SSTs are between 29-31c so plenty of oceanic heat available for development, and those conditions can support a pretty intense hurricane.

Edited September 7, 2011 by Paranoid

[Cookie]

[Somerset Squall]

I think Nate is another example of how quickly storms can spin up in the BOC. NHC note that the dry air west of Nate shouldn't be a problem as shear is low, therefore the dry air shouldn't make it's way into Nate's core. With low shear in the BOC and western GOM, Nate is expected to become a hurricane. Provided shear doesn't increase, Nate has plenty of time to become a decent hurricane.

[knocker]

WTNT45 KNHC 081458

TCDAT5

TROPICAL STORM NATE DISCUSSION NUMBER 4

NWS NATIONAL HURRICANE CENTER MIAMI FL AL152011

1000 AM CDT THU SEP 08 2011

EARLY MORNING VISIBLE SATELLITE IMAGES SHOW A MORE ORGANIZED

TROPICAL CYCLONE THAN WAS SEEN LATE YESTERDAY AFTERNOON. NATE HAS

THE APPEARANCE OF A SHEARED TROPICAL CYCLONE WITH THE CENTER

LOCATED NEAR THE NORTHEASTERN TIP OF THE MAIN CONVECTIVE MASS. THE

INITIAL WIND SPEED IS RAISED TO 45 KT...BASED ON A SHIP OBSERVATION

OF 40 KT TO THE SOUTHEAST OF THE CENTER...AND RECENT STRONGER WIND

REPORTS FROM ELEVATED PEMEX OIL RIGS IN THE BAY OF CAMPECHE. AN

AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO

INVESTIGATE NATE THIS AFTERNOON AND SHOULD PROVIDE A BETTER

ASSESSMENT OF THE INTENSITY.

NATE HAS NOT MOVED MUCH OVERNIGHT OR THIS MORNING...ALTHOUGH THE

LATEST SATELLITE AND MICROWAVE IMAGERY SUGGESTS THAT THE CENTER IS

A LITTLE SOUTH OF THE EARLIER ESTIMATES. THE CYCLONE IS FORECAST TO

REMAIN IN A WEAK STEERING PATTERN BETWEEN MID-LEVEL RIDGES OVER

MEXICO AND THE NORTHERN CARIBBEAN DURING THE NEXT 12-24 HOURS. IN A

DAY OR SO...NATE IS EXPECTED TO MOVE SLOWLY NORTHWARD AROUND THE

WESTERN PERIPHERY OF THE CARIBBEAN RIDGE. AFTER 36-48 HOURS...THE

MODEL SPREAD BECOMES INCREASINGLY LARGE...AS SUBTLE DIFFERENCES IN

THE STRENGTH AND ORIENTATION OF A MID/UPPER-LEVEL LOW AND TROUGH

EXTENDING FROM THE OHIO VALLEY SOUTHWESTWARD HAVE SIGNIFICANT

IMPLICATIONS ON THE FUTURE TRACK OF THE CYCLONE. THE LATEST GFS AND

GFDL MODELS...WHICH SHOW A SLIGHTLY DEEPER TROUGH...MOVE NATE

NORTHWARD TOWARD THE NORTHERN GULF COAST. THE ECMWF AND NOGAPS

MODELS DEPICT A WEAKER TROUGH THAT DOES NOT CAPTURE NATE AND ALLOWS

IT TURN TURN WESTWARD TOWARD MEXICO TO THE SOUTH OF A BUILDING

RIDGE...ALTHOUGH IT SHOULD BE NOTED THAT THERE IS CONSIDERABLE

SPREAD AMONG THE ECMWF ENSEMBLE MEMBERS. THE OFFICIAL FORECAST HAS

BEEN SHIFTED TO THE RIGHT AND LIES BETWEEN THESE TWO VIABLE

SCENARIOS BUT HAS NOT BEEN SHIFTED AS FAR AS THE TVCA CONSENSUS.

THE NOAA G-IV AIRCRAFT IS SCHEDULED TO PERFORM A SYNOPTIC

SURVEILLANCE MISSION LATER TODAY...WHICH WILL HOPEFULLY HELP REDUCE

THE SPREAD IN THE TRACK GUIDANCE TONIGHT.

NATE IS CURRENTLY LOCATED IN AN ENVIRONMENT OF LIGHT TO MODERATE

NORTHEASTERLY SHEAR. THE SHEAR IS FORECAST TO LESSEN DURING THE

NEXT DAY OR SO...WHICH SHOULD ALLOW FOR GRADUAL STRENGTHENING.

LATER IN THE FORECAST PERIOD...SOUTHWESTERLY SHEAR IS EXPECTED TO

INCREASE AND ALONG WITH DRIER LOW- TO MID-LEVEL AIR...IS FORECAST TO

SLOW THE INTENSIFICATION PROCESS. THE UPDATED INTENSITY FORECAST IS

SIMILAR TO THE PREVIOUS ADVISORY AND IS IN GOOD AGREEMENT WITH THE

SHIPS/LGEM GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 20.0N 92.4W 45 KT 50 MPH

12H 09/0000Z 20.4N 92.2W 55 KT 65 MPH

24H 09/1200Z 21.0N 92.2W 55 KT 65 MPH

36H 10/0000Z 21.8N 92.7W 60 KT 70 MPH

48H 10/1200Z 22.5N 93.2W 65 KT 75 MPH

72H 11/1200Z 23.1N 93.8W 70 KT 80 MPH

96H 12/1200Z 23.6N 94.4W 70 KT 80 MPH

120H 13/1200Z 24.0N 95.0W 70 KT 80 MPH

$$

FORECASTER BROWN

[Somerset Squall]

Recon have found winds justifying increasing the intensity to 60kts. Nate is now officially forecast to become a cat 2. Nate has been practically stationary today, but should begin to move to the north as the storm grows stronger.

[Somerset Squall]

Overall, Nate has moved pratically nowhere since the storm formed two days ago. This has taken it's toll on the storm. Upwelling has occcured beneath Nate, cooling the waters the storm is parked over. Also, dry air to the north has filtered into Nate. Though Nate's LLC is well defined, convection is sparse. NHC still forecast strengthening, but are not as bullish as before. Nate is now expected to finally move towards the west as ridging to the north builds, and make landfall in Mexico in around 48hrs time.

Edited September 9, 2011 by Somerset Squall

[Somerset Squall]

In post storm analysis, Nate has been upgraded to a hurricane (was originally thought to peak at 60kts).

Air Force Reserve Hurricane Hunter aircraft flew a total of six missions in Nate and

obtained sixteen fixes. The maximum observed flight-level wind (850 mb) in Nate was 82 kt

southeast of the center at 1815 UTC on 8 September. The 82-kt 850 mb observation would

typically support an estimate intensity of 65 kt. However, the maximum coincident SFMR wind

estimate was only 60 kt, and operationally Nate was not upgraded to a hurricane, in part because

of its satellite appearance. Data received in post-analysis from Eco-1, a Petróleos Mexicanos

(PEMEX) oil rig located about 45 n mi southeast of the center (Fig. 4), indicated a 1-minute

sustained wind of 72 kt at an elevation of 30 m several hours after the time of the peak winds

measured by the aircraft in a convective band southeast of the center. An adjustment of these

winds to the standard 10 m height using the mean hurricane dropwindsonde profile yields a peak

surface sustained wind of 67 kt. These data and the earlier reconnaissance measurements

support the estimate of Nate’s peak intensity of hurricane strength.

http://www.nhc.noaa.gov/data/tcr/AL152011_Nate.pdf