Tropical storm Debby

[Guest Mr_S]

I'm very impressed with Td4 this morning given the amoun tof SAL that is still coming from Africa.

Sorry to be a newbie, whats SAL?? Saturated anabolic lapse is a wild card guess and still means nothing to me when comparing to a TD or above :blush:

[parmenides3]

Sorry to be a newbie, whats SAL?? Saturated anabolic lapse is a wild card guess and still means nothing to me when comparing to a TD or above :blush:

That's what I asked on the Atlantic waves thread!

Here:

Here's a little thing about it parmenides:

http://www.aoml.noaa.gov/hrd/tcfaq/A17.html

from Kold Weather

P

[Paranoid]

We have Debby!

TROPICAL STORM DEBBY ADVISORY NUMBER 6

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006

1100 PM AST TUE AUG 22 2006

...TROPICAL DEPRESSION STRENGTHENS INTO THE FOURTH TROPICAL STORM

OF THE SEASON OVER THE FAR EASTERN ATLANTIC OCEAN...

AT 1100 PM AST...0300Z...THE CENTER OF TROPICAL STORM DEBBY WAS

LOCATED NEAR LATITUDE 15.2 NORTH...LONGITUDE 28.9 WEST OR ABOUT

300 MILES...485 KM...WEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

DEBBY IS MOVING TOWARD THE WEST-NORTHWEST NEAR 18 MPH...30 KM/HR...

AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24

HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/HR...WITH HIGHER

GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM

FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB...29.62 INCHES.

REPEATING THE 1100 PM AST POSITION...15.2 N...28.9 W. MOVEMENT

TOWARD...WEST-NORTHWEST NEAR 18 MPH. MAXIMUM SUSTAINED WINDS...40

MPH. MINIMUM CENTRAL PRESSURE...1003 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER

AT 500 AM AST.

$$

FORECASTER STEWART

GFDL thinks this storm will reach a peak of 112kts at flight level and a minimum pressure of 971hpa. Then again, it said all the others would become hurricanes too.

Edited August 23, 2006 by Paranoid

[parmenides3]

Name change, mods? Or new thread?

:blush: P

[kold weather]

As expected TD-4 has been upgraded overnight to tropical storm Debby. Debby is looking pretty solid though the convection is pretty shallow, for reasons I'll explain later. Still the system is pretty well organised and is almost certainly a tropical storm, with the latest models keeping Debby at 35kts.

Track remians the same and Debby should re-curve away from the states and should stay to the east of Bermuda even. There is very strong agreement between the models for such a re-curve:

http://euler.atmos.colostate.edu/~vigh/gui...ntic/early2.png

So there probably isn't nothing for people in the US to fear about from this system though it will probbly affect our weather in some way.

Strength-wise I don't think it'll deepen too fast, at least not for the next 24-48hrs given it'll be over only marginal temperature water, around 26C which is the bottom end for most normal tropical cyclones to develop at the latitude its at. This is evident in the convection which is pretty shallow in nature which is thanks to the marginal sea temps. Added to this you've still got some fairly dry air that ebby will probably have to push through, even if it isn't gonig to be as much as a problem s it was for Chris as the air is mixing more readily this time, it still could limit debby for a while. So only expect slow development for a little while.

Once its gone from that region the air beocmes more moist again and the sea temps start to rise again which should help convection to strengthen up and should help to make the system stronmger faster, so past 24-48hrs we should see some more steady strengthening of Debby and unless we see some shear I should think Debby should eventually become a hurricane though quite how strong I'm not sure, I'd punt for a moderate category-2, say 100mph.

[kold weather]

Debby still steadily getting stronger, models are being started at 45kts which means that debby will be be upped to 45kts or 50mph:

(ps, worth noting that the SHIPS just shy away from making it a hurricane but Debby is getting stronger faster then the models predcicted.)

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO TPC/NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONES.

NATIONAL HURRICANE CENTER NORTH ATLANTIC OBJECTIVE AIDS FOR

TROPICAL STORM DEBBY (AL042006) ON 20060823 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...

060823 1200 060824 0000 060824 1200 060825 0000

LAT LON LAT LON LAT LON LAT LON

BAMD 16.4N 30.8W 18.0N 33.2W 19.6N 35.4W 21.4N 37.8W

BAMM 16.4N 30.8W 18.2N 33.2W 20.0N 35.7W 21.8N 38.2W

A98E 16.4N 30.8W 17.8N 33.5W 19.2N 36.1W 20.8N 38.6W

LBAR 16.4N 30.8W 18.1N 33.2W 19.6N 35.6W 21.0N 38.3W

SHIP 45KTS 51KTS 56KTS 59KTS

DSHP 45KTS 51KTS 56KTS 59KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...

060825 1200 060826 1200 060827 1200 060828 1200

LAT LON LAT LON LAT LON LAT LON

BAMD 23.3N 40.1W 26.8N 43.5W 29.6N 44.7W 33.3N 42.3W

BAMM 23.4N 40.4W 26.0N 44.3W 28.4N 46.8W 32.0N 46.1W

A98E 22.6N 41.1W 26.4N 46.0W 30.4N 48.7W 36.9N 44.2W

LBAR 22.2N 41.2W 24.6N 46.1W 27.7N 49.2W 28.1N 52.3W

SHIP 60KTS 60KTS 58KTS 56KTS

DSHP 60KTS 60KTS 58KTS 56KTS

...INITIAL CONDITIONS...

LATCUR = 16.4N LONCUR = 30.8W DIRCUR = 300DEG SPDCUR = 15KT

LATM12 = 14.9N LONM12 = 28.2W DIRM12 = 299DEG SPDM12 = 15KT

LATM24 = 13.4N LONM24 = 25.3W

WNDCUR = 45KT RMAXWD = 30NM WNDM12 = 35KT

CENPRS = 1000MB OUTPRS = 1011MB OUTRAD = 225NM SDEPTH = D

RD34NE = 45NM RD34SE = 45NM RD34SW = 45NM RD34NW = 45NM

Debby looks very healthy this morning, a large dome of convection is ovedr the center which may well be the start of a CDO (central dense overcast.) which will probably help it against the drier air to its north-west wher eits heading. Should it make it through that mass of dry air then depsite shear strengthening it should be organised enough to survive the slight rise in shear and it has good prospects and will have every chance at becoming a hurricane by the weekend.

[crimsone]

Time for an update on the visuals I think - models and water vapour...

[kold weather]

Latest update confirms the increase in widspeeds upto 45kts and had the tropical storm eventually becoming a hurricane right towards the end despite the increase of shear from the trough that is diving down throug hthe weakness, though i have a feeling this may be slightly overdone by the models.

http://www.skeetobiteweather.com/archive/f...AL042006lts.gif

Latest advisory discussion, all very similar to the last one as well and pretty much among the same lines that I'm talking about proving i'mnot just making this stuff up as i go along!!!

I'd think cooler SST's ahea dof it and drier air (As evident by Crimsone's water vapor image above this post.) will prevent much more strengthening for a little while. Still heres the latest disucssin from the NHC:

ZCZC MIATCDAT4 ALL

TTAA00 KNHC DDHHMM

TROPICAL STORM DEBBY DISCUSSION NUMBER 8

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006

1100 AM EDT WED AUG 23 2006

DEBBY APPEARS TO BE SLOWLY STRENGTHENING...BASED ON THIS MORNING'S

QUIKSCAT PASS THAT HAD A COUPLE OF BELIEVABLE 45 KT VECTOR. THE

SYSTEM ALSO SHOWED VERY GOOD ORGANIZATION ON AN 11Z MICROWAVE PASS.

CONVENTIONAL SATELLITE IMAGERY DOES NOT YET REFLECT THAT LEVEL OF

ORGANIZATION...AND DVORAK INTENSITY ESTIMATES RANGE FROM 35 TO 45

KT. THE SYSTEM IS MAINTAINING FAIRLY GOOD OUTFLOW UNDER LIGHT

EASTERLY SHEAR. THE THERMODYNAMIC ENVIRONMENT IS EXPECTED TO

SUPPORT ONLY SLOW DEVELOPMENT FOR THE NEXT COUPLE OF DAYS...BUT

DEBBY WILL BE MOVING BACK OVER WARMER WATERS AFTER THAT. GLOBAL

MODELS CONTINUE TO SUGGEST THAT AN UPPER LOW WILL CAUSE AN INCREASE

IN SOUTHERLY SHEAR LATE IN THE PERIOD THAT COULD SLOW THE

INTENSIFICATION. NEVERTHELESS...THE EXPLICIT INTENSITY GUIDANCE

CONTINUES TO INDICATE GRADUAL DEVELOPMENT TO NEAR HURRICANE

STRENGTH AND SO DOES THE OFFICIAL FORECAST.

THE INITIAL MOTION IS 300/15. DEBBY CONTINUES TO BE STEERED BETWEEN

WEST-NORTHWESTWARD AND NORTHWESTWARD AROUND THE SOUTHWESTERN

PERIPHERY OF A MID-TO UPPER-LEVEL HIGH CENTERED NEAR THE AZORES.

THERE HAS BEEN NO CHANGE TO THE BASIC SYNOPTIC THINKING. A

SIGNIFICANT WEAKNESS IN THE SUBTROPICAL RIDGE IS EXPECTED TO

DEVELOP AS A MID- TO UPPER-LEVEL TROUGH AMPLIFIES OVER THE CENTRAL

ATLANTIC LATE IN THE FORECAST PERIOD. ALL GUIDANCE MODELS EXCEPT

THE NOGAPS BEGIN A RECURVATURE BY DAY 5...AND THE NOGAPS DOES SO

SHORTLY THEREAFTER. THERE HAS BEEN VERY LITTLE CHANGE TO THE

OFFICIAL FORECAST TRACK AT THIS TIME...BUT I NOTE THAT MOST OF THE

GUIDANCE SHOWS A HARDER RIGHT TURN BY DAY 5 THAN THE OFFICIAL

FORECAST DOES.

FORECAST POSITIONS AND MAX WINDS

INITIAL 23/1500Z 16.8N 31.5W 45 KT

12HR VT 24/0000Z 17.8N 33.6W 50 KT

24HR VT 24/1200Z 19.1N 36.5W 55 KT

36HR VT 25/0000Z 20.3N 39.3W 55 KT

48HR VT 25/1200Z 21.6N 42.2W 55 KT

72HR VT 26/1200Z 24.5N 47.5W 60 KT

96HR VT 27/1200Z 27.5N 51.0W 65 KT

120HR VT 28/1200Z 30.5N 53.0W 65 KT

Edited August 23, 2006 by kold weather

[kold weather]

Debby slightly weakened overnight thanks to areduction of convection however actualy over recenthours it has regained some of the dee convection that choked it yesterday and overnight, prehaps a signal that its moved through the most dense of the dry air and now getting back into more moist profiles.

Anyway Debby is probably once again a 45kt tropical storm i suspect and still slowly making its way WNW/NW. A steady strengthening still expected, though the seas are starting to re-warm again in front of the system shear is set to increase as the trough opens the weakness in the the large ridge complex to its NW so there probably won't be much net gain, though the more moist air and higher sea temps should see it getting art least upto strong tropical storm status and i still think it could make it to hurricane eventually.

[Hurricane Debby]

UPDATED: 11:55 pm EDT, August 23, 2006

TROPICS ABOUT TO BECOME NEWS MAKER AGAIN

Debby is not of much concern to any land areas and should continue to move on out to the open ocean as it slowly intensifies. Debby could become our first hurricane of this season. No matter how strong it gets, it will not be an issue for anyone except shipping interests.

Of greater concern now is the tropical wave/low pressure area that is approaching the Windward Islands. It looks as though this will go on and develop in to a tropical depression and likely a storm. In fact, the GFDL computer model shows it becoming a strong hurricane as it heads in to the northwest Caribbean Sea. Even the NHC's intensity model shows this becoming a hurricane. Needless to say, we will want to keep a close watch on the future of this system. People in the Windwards can expect squally weather for the next day or so as the wave and its energy passes through the region. The Hurricane Hunters should be out tomorrow and will give us a clearer picture of what is happening with this system.

Courtesy Hurricane Track

[parmenides3]

Congratulations, HD! At last, your heart's desire.

[Hurricane Debby]

[crimsone]

Is it just me, or do these tropical cyclones in the atlantic not want to dip below the 1000 mb mark so far this year? :lol:

Perhaps debby will do so tomorrow. Currently, the pressure is 1000 mb and the windspeed is 45kt with gusts to 55 kt. From what I've seen of advisories and outlooks so far this year, that suggests that it's not far away from the sustained speed reaching 50kt. Perhaps tomorrow :lol:

[Hurricane Debby]

Today I am still a curve out at sea but slowly gaining strength.....

Come on - do something !

[kold weather]

It's really not going to get that much stronger then waht it is now, the problem for Debby is that while SST's and the ehat content are going to increase along with it shear is also going to increase so any benifit from the more favorable ocean is going to be lost by the increasing shear that the trough to its north induces.

[parmenides3]

It's really not going to get that much stronger then waht it is now, the problem for Debby is that while SST's and the ehat content are going to increase along with it shear is also going to increase so any benifit from the more favorable ocean is going to be lost by the increasing shear that the trough to its north induces.

In addition to which, there appears to be plenty of very dry air in Debby's track, in whichever direction she goes. :lol:

[Hurricane Debby]

Gutted !! Well if I can't wreak havoc over there maybe we will get the dregs of her over here and I can wreak havoc here instead !

What a wash out. So much for being a Cat 5 and retired

[Somerset Squall]

Is it just me, or do these tropical cyclones in the atlantic not want to dip below the 1000 mb mark so far this year? :lol:

Indeed :lol: . Though saying that Alberto did dip to 995mb.

[crimsone]

LOL Atmosphere. I'd forgotten about that. I didn't think that Alberto had gotten there either. Thanks, because now I've corrected my statement in Ernestos thread.

This thread title needs changing now though, and Debby is now a Tropical Depression.

It seems that there is now some uncertainty over where exactly it wants to go after the turn. The models seem to agree on where the turn will be, and roughly how sharp it will be, but there seems to be a spilt over how early to finish the turn and where Debby will go afterwards.

BAMD, and GFDL want to take it to the NW.

BAMM, A98E, Lbar want to take it WNW

UKMET and NHC don't have long enough runs to say for sure what they are thinking, but they at least appear to be going for the NW option.

Of course, Where it is in the atlantic, even where the models roughly agree NW, just a 10 degree difference in the direction can make a heck of a difference as to where its actually heading towards. (not that it'll make landfall, but it could still have an effect on somebodies weather)

Edited August 26, 2006 by crimsone