ATL: DANNY - Remnants - Discussion

[Gustywind]

000
WTNT34 KNHC 221500
TCPAT4

BULLETIN
HURRICANE DANNY ADVISORY NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015
1100 AM AST SAT AUG 22 2015

...DANNY STILL SLOWLY WEAKENING...
...TROPICAL STORM WATCH ISSUED FOR PORTIONS OF THE LEEWARD
ISLANDS...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.4N 52.0W
ABOUT 660 MI...1060 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Meteorological Service of Antigua has issued a tropical storm
watch for Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla.

The Meteorological Service of Curacao has issued a tropical storm
watch for Saba and St. Eustatius.

The Meteorological Service of St. Maarten has issued a tropical
storm watch for St. Maarten.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and
Anguilla
* Saba and St. Eustatius
* St. Maarten

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

[northjaxpro]

Initial 15,2 N / 50,8 W, NOW 15.3N/ 51,4 W, the turn to the west has begun

I think so and the forward speed should increase.

Let's wait a bit and see if this tendency continues.

11 am advisory from NHC has Danny on a 285 degree header. Still moving west-northwest for the time being.

[NDG]

I'm not sure what the disagreement has been in the long term forecast (beyond 5 days)? It's never going to match exactly with the nature of the time frame anyway. Both the Euro/GFS/Ensembles are generally in agreement an eastern conus trof will impact, west or east it's still there. Likely assisted by the recurve of Atsani and Goni. We're talking about a rare 2-3 Sigma wave breaking event in the North Pacific which supports a very deep trough. If it was in the Bahamas by then, odds are the coming trof would shunt it out anyway. Assuming guidance consensus is correct.

The disagreement between the two models is how deep the ML trough and orientation of the ML trough will be. The GFS showed a much deeper trough compared to the Euro which is not as deep and with a more positive tilt by day 6.

[NDG]

It sounds like a good compromised forecast for now.

Sounds like a recipe for disaster in the prime spot in the basin where the Labor Day storm formed and the potential for a blown missed forecast.

There's still plenty of time to watch how things shape up either way.

[NDG]

My SSD map says SST's are only around 28c in current area.

That in my books is not marginal, that's plenty warm to fuel a hurricane.

[northjaxpro]

NHC 120 hr forecast in the 11 a.m. advisory has Danny as a 30 kt tropical depression approaching the Central Bahamas.

[Gustywind]

11 am advisory from NHC has Danny on a 285 degree header. Still moving west-northwest for the time being.[/quote]
West turn should come soon given the last discussion from 11AM. Let's wait and see what really happens.

From NHC discussion.

"The initial motion is now 285/10. There is no change in the forecast philosophy from the previous advisory, with Danny expected
to turn westward and accelerate later today as the subtropical ridge to the north of the cyclone builds westward and strengthens".

[Ntxw]

The disagreement between the two models is how deep the ML trough and orientation of the ML trough will be. The GFS showed a much deeper trough compared to the Euro which is not as deep and with a more positive tilt by day 6.

I think for a 7 day forecast that's about as good as we will see until closer range. It's a higher confidence forecast per say if one were showing an eastern ridge that'll pull some hairs . The last trough this past week was much deeper than either model showed 7+ days out. I think the Pacific is on steroids with the re-curves and should dig some pretty deep troughs.

One thing for sure Danny is still very small. If convection is still left when he nears the islands a few miles difference could mean very little impact or some impacts if it were right over.

For PR definitely want to see it continue to weaken and increase in areal coverage otherwise may not make much of a dent to rainfall deficits

[Weatherboy1]

It sounds like a good compromised forecast for now.

Sounds like a recipe for disaster in the prime spot in the basin where the Labor Day storm formed and the potential for a blown missed forecast.

Yeah I tend to agree the forecast could be blown one way or the other - either Danny dissipates completely because shear and dry air work faster ... Or he misses the islands, the shear isn't as bad, and he gets into a much more favorable area to strengthen 4-5 days out. Just my opinion; listen to the experts

[TheStormExpert]

From the 11am Discussion.

The intensity forecast becomes lower confidence at days 4 and 5 due to
the uncertainty in how much land Danny will encounter, disagreements
between the dynamical models over the forecast shear, and continued
divergence between the models forecasting Danny to dissipate and the
models forecasting it to survive. The latter part of the forecast
compromises between these extremes by showing a continued weakening
trend.

[ronjon]

If you examine the Euro a little further out in time, it breaks off the southern end of the east coast trough and retrogrades it over to the western gulf- southern plains. At the same time, it really pumps up the mid-level ridge over the Bahamas-Florida. I think at this long range, it's equally credible solution that whatever's left of Danny might continue moving W-NW thru the florida straits-S Fl.

[Sanibel]

That in my books is not marginal, that's plenty warm to fuel a hurricane.

It's a marginal increase above the waters it transitioned out of. Which is how I meant it. Which means it shouldn't add much to fight the shear.

[PTrackerLA]

Pretty strong trough modeled in both GFS and EURO for the gulf south. Low's in the mid 60's for the middle of next week, the coolest weather in about 3 months. Don't think any remnants will be able to make it that far west IMO.

[jinftl]

I don't envy the NHC - we may not be many advisories away from southeast florida being in the forecast cone - of either a system that could dissipate before it gets to the U.S. or not. I know the media machine turns on big time here once we are in a cone - in this case a cone of what?


From the NHC 11am Discussion - the TD status at day 5 is a 'blended' iotensity:

The intensity forecast becomes lower confidence at days 4 and 5 due to
the uncertainty in how much land Danny will encounter, disagreements
between the dynamical models over the forecast shear, and continued
divergence between the models forecasting Danny to dissipate and the
models forecasting it to survive. The latter part of the forecast
compromises between these extremes by showing a continued weakening
trend.

[tailgater]

If you examine the Euro a little further out in time, it breaks off the southern end of the east coast trough and retrogrades it over to the western gulf- southern plains. At the same time, it really pumps up the mid-level ridge over the Bahamas-Florida. I think at this long range, it's equally credible solution that whatever's left of Danny might continue moving W-NW thru the florida straits-S Fl.

Well Ronjon you are a TPK.
I just learned that term this morning doing the xword puzzle. We don't need or want anything going through the straits.

[tropicwatch]

One of the things that might be helping Danny or at least not hurting him, is that the mid level shear is fairly light.

[tropicwatch]

Still some northward progression.

http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20HURRICANE&lat=16.5&lon=-50&info=vis&zoom=2&width=1024&height=768&type=Animation&quality=92&palette=ir1.pal&numframes=7&mapcolor=gray

[tailgater]

What a difference a day can make.

It is still looking impressive.

[Gustywind]

TROPICAL CYCLONE ALERT STATEMENT

WHCA31 TAPA
HURRICANE DANNY ALERT STATEMENT
ANTIGUA AND BARBUDA METEOROLOGICAL SERVICES
12:30 PM ECT SAT AUG 22 2015

THIS IS FOR THE LEEWARD ISLANDS AND BRITISH VIRGIN ISLANDS

...DANNY WEAKENS TO A CATEGORY 1 HURRICANE, FURTHER WEAKENING IS EXPECTED...

A TROPICAL STORM WATCH MAY BE REQUIRED LATER TODAY FOR THE BRITISH VIRGIN ISLANDS.

RESIDENTS SHOULD STAND READY TO FULLY EXECUTE THEIR STORM PLANS TO PROTECT LIFE AND PROPERTY.

DANNY IS MOVING FURTHER INTO A HOSTILE UPPER-LEVEL WIND ENVIRONMENT. HENCE, THE WEAKENING TREND IS EXPECTED TO CONTINUE, RESULTING IN THE SYSTEM BEING DOWNGRADED TO A TROPICAL STORM BY SUNDAY WITH FURTHER WEAKENING BEFORE REACHING THE ISLANDS LATE MONDAY.

AT 11 AM ECT OR 1500 UTC, THE CENTRE OF WEAKENING HURRICANE DANNY WAS LOCATED NEAR LATITUDE 15.4 NORTH, LONGITUDE 52.0 WEST OR ABOUT 850 MILES EAST-SOUTHEAST OF TORTOLA.

DANNY IS MOVING TOWARD THE WEST-NORTHWEST AT 12 MPH. AN INCREASE IN FORWARD SPEED IS EXPECTED LATER TODAY OR TONIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 90 MPH WITH HIGHER GUSTS. ADDITIONAL WEAKENING IS FORECAST DURING THE NEXT 48 HOURS.

DANNY REMAINS A VERY SMALL CYCLONE WITH HURRICANE FORCE WINDS EXTENDING OUTWARD UP TO 15 MILES FROM THE CENTRE, AND TROPICAL STORM FORCE WINDS EXTENDING OUTWARD UP TO 60 MILES.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 984 MB OR 29.06 INCHES.

ON ITS PRESENT TRACK, DANNY WILL BE NEAR OR OVER THE BRITISH VIRGIN ISLANDS LATE MONDAY.

DANNY COULD IMPACT THE ISLANDS WITH SUSTAINED WINDS OF AROUND 50 MPH OR LESS, BUT PEAK GUSTS OF AROUND 70 MPH ARE POSSIBLE.

RAINFALL TOTALS OF 1-4 INCHES ARE POSSIBLE WITH LOCALLY HIGHER AMOUNTS. MODERATE FLOODING COULD OCCUR AND A FLOOD WATCH OR WARNING MAY BE REQUIRED FOR MONDAY.

LARGE BATTERING WAVES ARE EXPECTED DURING THE PASSAGE OF DANNY. SEAS WILL PEAK NEAR 3.7 METRES OF 12 FEET. MARINERS WILL NEED TO SEEK SAFE ANCHORAGE FOR THEIR VESSELS.

RESIDENTS ARE URGED TO CLOSELY MONITOR THE BULLTIN COMING OUT OF THE MET OFFICE FOR STORM SPECIFIC INFORMATION TAILORED FOR OUR ISLANDS.

REPEATING THE 11 AM ECT POSITION, 15.4 N, 52.0 W. MOVEMENT TOWARD THE WEST-NORTHWEST NEAR 12 MPH. MAXIMUM SUSTAINED WINDS ARE NEAR 90 MPH. THE MINIMUM CENTRAL PRESSURE IS 984MB.

THE NEXT ADVISORY FROM THE MET OFFICE WILL BE AT AROUND 2:45 PM ECT

CLICK HERE FOR MORE INFORMATION

FORECASTER DALE DESTIN

[ConvergenceZone]

based upon how it looks now, I think it's going to fall apart faster than predicted.

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