Tropical Storm Danny Satellite Images Show Better Organization-Spaghetti Model Persistent




Tropical Storm Danny 1415Z 08.27.09

Tropical Storm Danny 1415Z 08.27.09



TS Danny Spaghetti Model 12Z 08.27.09

TS Danny Spaghetti Model 12Z 08.27.09



TS Danny Spaghetti Model Intensity 12Z Thu

TS Danny Spaghetti Model Intensity 12Z Thu



NHC Fcst Track 11am Thursday

NHC Fcst Track 11am Thursday



Tropical Storm Danny Water Vapor 12Z 08.27.09

Tropical Storm Danny Water Vapor 12Z 08.27.09

Tropical Storm Danny continues to have problems as it is still sandwiched between upper level lows.  This has resulted in upper winds coming together which is the opposite of what you need for a hurricane to develop.  Consequently, it doesn’t look very good.  But, Dr. Jack Beven at the National Hurricane Center reports late this morning that the overall circulation is getting better looking.  But, I see, and he notes, that the convection and best stuff is generally disjointed to the north and northeast of the center of low level circulation.  Now, over the next day or so, the upper level lows will move out and an upper level high is expected to take its place over the top of Danny.  That is the chance that it needs to develop and become better organized. 




Tropical Storm Danny 14:45Z Dvorak 08.27.09

Tropical Storm Danny 14:45Z Dvorak 08.27.09

Now, the official forecast calls for Danny to start to move north and stay just off the east coast as it develops into a minimal hurricane.  However, previously there was only one model that had the storm scraping the US coast.  Now there are three.  The Canadian model has been the most consistent in this regard.  The other two are the US Navy NOGAPS and the more conventional NAM.  The tropical models do not suggest this.  But, I am wondering if, since the storm has not truly been tropical in nature, if the non-tropical storms initially have a better handle on the system.  Also, the storm keeps on either reforming or drifting farther west than what the tropical models have been calling for.  This is why I am still of the mind that the storm may in fact at least partially move along the Carolina coast.  On the other hand, if this guy lolligags out in the ocean much longer, another big, unseasonable trof like the one that caught Bill will be digging into the Ohio Valley and will pick it up before it ever gets to the coast.  There is a consensus among the models that the storm will deepen as it moves northward and gets even with the middle of the Atlantic coast.   They also point toward an impact on Nova Scotia.  However, there are some problems  with  the developmental scenario brought forth by the models that conflict with conventional wisdom as Dr. Beven points out at the bottom of the post.




Canadian Model 996 mb Low near Hattaras valid Friday Evening derived 00Z Thu

Canadian Model 996 mb Low near Hattaras valid Friday Evening derived 00Z Thu



Danny Visible Satellite Image 1445Z 08.27.09

Danny Visible Satellite Image 1445Z 08.27.09

WTNT45 KNHC 271449
TCDAT5
TROPICAL STORM DANNY DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052009
1100 AM EDT THU AUG 27 2009


DANNY HAS BECOME A LITTLE BETTER ORGANIZED THIS MORNING.  THE
LOW-LEVEL CIRCULATION LOOKS BETTER DEFINED THAN IT DID YESTERDAY…
AND THE CONVECTION IS CLOSER TO THE CENTER.  THAT BEING SAID…THE
CENTER IS STILL EXPOSED…THE CONVECTION HAS MORE OF A LINEAR
CHARACTER THAN THE CURVED BANDS CHARACTERISTIC OF A TROPICAL
CYCLONE…AND THE STRONGEST WINDS ARE STILL WELL REMOVED FROM THE
CENTER.  THE INITIAL INTENSITY IS HELD AT 50 KT PENDING THE NEXT
AIR FORCE RESERVE HURRICANE HUNTER MISSION AT 18Z…ALTHOUGH RECENT
QUIKSCAT DATA SUGGESTS THIS COULD BE A LITTLE GENEROUS.


THE EXPOSED LOW-LEVEL CENTER HAS BEEN MOVING ALMOST DUE WESTWARD FOR
THE PAST FEW HOURS.  IT IS UNCLEAR IF THIS IS REPRESENTATIVE OF THE
ACTUAL MOTION OF DANNY OR A SHORT-TERM TREND.  SO…THE INITIAL
MOTION IS AN UNCERTAIN 310/11.  DESPITE THE PROBLEMATIC INITIAL
MOTION…THE TRACK GUIDANCE MODELS ARE IN EXCELLENT AGREEMENT THAT
DANNY SHOULD TURN NORTHWARD OVER THE NEXT 24-36 HR IN ADVANCE OF A
COMPLEX DEEP-LAYER TROUGH MOVING INTO THE EASTERN UNITED STATES.
AFTER THAT…THE STORM SHOULD ACCELERATE NORTHEASTWARD INTO THE
WESTERLIES…PASSING NEAR OR OVER NEW ENGLAND AND THE CANADIAN
MARITIMES ON ITS WAY INTO THE NORTH ATLANTIC.  THE
NAM…NOGAPS…AND CANADIAN MODELS ARE ON THE LEFT SIDE OF THE
GUIDANCE ENVELOPE… CALLING FOR THE CENTER TO PASS NEAR CAPE
HATTERAS AND THEN OVER NEW ENGLAND.  THE GFS…GFDL…AND HWRF ARE
ON THE RIGHT SIDE…CALLING FOR THE CENTER TO STAY OFFSHORE UNTIL
IT REACHES NOVA SCOTIA.  THE NEW FORECAST TRACK IS ADJUSTED TO THE
LEFT OF THE PREVIOUS TRACK FOR THE FIRST 48 HR BASED ON THE INITIAL
POSITION AND MOTION…AND IT LIES DOWN THE MIDDLE OF THE GUIDANCE
ENVELOPE.  WHILE THE FORECAST TRACK DOES NOT CURRENTLY SHOW DANNY
MAKING LANDFALL IN THE UNITED STATES…ADDITIONAL MOTION TO THE
LEFT OF THE TRACK COULD BRING THE CENTER NEAR OR OVER THE U. S.
EASTERN SEABOARD.


DANNY IS CURRENTLY IN AN AREA OF UPPER-LEVEL CONFLUENT FLOW
ASSOCIATED WITH THE PERSISTENT CYCLONIC SHEAR AXIS SEEN IN WATER
VAPOR IMAGERY.  THE LARGE-SCALE MODELS FORECAST THIS FEATURE TO BE
REPLACED BY AN UPPER-LEVEL ANTICYCLONE DURING THE NEXT 24-30 HR…
AND IF THIS VERIFIES IT WILL GIVE DANNY ITS BEST CHANCE TO
STRENGTHEN.  BASED ON THIS…THE INTENSITY FORECAST CALLS FOR DANNY
TO STRENGTHEN DURING THE 24-48 HR PERIOD…WITH A PEAK INTENSITY OF
65 KT.  THE GUIDANCE AGREES THAT DANNY SHOULD START LOSING TROPICAL
CHARACTERISTICS AND INTENSITY AFTER 48 HR AS IT BECOMES EMBEDDED IN
A STRONG BAROCLINIC ENVIRONMENT.  OVERALL…THE INTENSITY FORECAST
IS IN BEST AGREEMENT WITH THE INTENSITY CONSENSUS…WITH THE PEAK
INTENSITY BELOW THAT OF THE HWRF AND GFDL MODELS.


FORECAST POSITIONS AND MAX WINDS


INITIAL      27/1500Z 27.5N  73.1W    50 KT
12HR VT     28/0000Z 28.7N  73.9W    50 KT
24HR VT     28/1200Z 30.3N  74.5W    55 KT
36HR VT     29/0000Z 33.2N  74.3W    60 KT
48HR VT     29/1200Z 36.9N  72.4W    65 KT
72HR VT     30/1200Z 45.0N  64.5W    60 KT…EXTRATROPICAL
96HR VT     31/1200Z 50.0N  53.0W    45 KT…EXTRATROPICAL
120HR VT     01/1200Z 52.5N  37.0W    30 KT…EXTRATROPICAL


$$
FORECASTER BEVEN

There are no comments on this post.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: