Model Comparison HPC

[Dean4Storms]

In case you are wondering what the ETA shows with Ivan, it takes him just to the south of Jamaica and the Caymans toward the Yucatan channel and the Canadian likewise. After seeing the turn back to more 275-280 tonight, it looks more likely.

Read Below.....

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
109 PM EDT WED SEP 08 2004

VALID SEP 08/1200 UTC THRU SEP 11/0000 UTC

MODEL INITIALIZATION...

SURFACE...
THE 12Z ETA AND GFS ARE INITIALIZED VERY WELL... THE ETA IS A BIT
SOUTH OF THE INITIAL POSITION OF TD FRANCES.

500 MB...
THE ETA AND GFS ARE VERY REASONABLE AT 500 MB. THE ETA HAS A
FEW SHORTCOMINGS INITIALLY... HEIGHTS TOO HIGH WITH A WEAK
SHORT WAVE MOVING THROUGH THE ID AND THE NRN ROCKIES AND
NOT PHASING THE WESTERLIES AND TD FRANCES OR 582 HEIGHT LINE
DIPPING INTO THE SRN APPALACHIANS. CONCERNING THE 588
SUBTROPICAL RIDGE EXTENDING INTO FL AND THE CARIBBEAN... THE
ETA SEEMS TO HAVE A BETTER INITIALIZATION THAN THE GFS ON THE
WRN EDGE RIDGE AXIS EXTENDING THROUGH CUBA AND INTO THE ERN
GULF OF MEXICO.

MOISTURE...
BOTH MODELS ARE VERY WELL INITIALIZED WITH MOISTURE ACROSS
THE CONUS... ESPECIALLY CONCERNING TD FRANCES.


MODEL TRENDS...

ETA...
THE 12Z ETA WHEN COMPARED TO THE 00Z/08 VERSION FROM LAST
NIGHT SHOW A FEW TRENDS OVER THE 60 HR FCST PERIOD. FIRST
OFF... THE 12Z ETA IS PROGRESSING QUICKER IN LIFTING FRANCES TO
THE NORTH AND EAST OVER THE FIRST 48 HRS. SECOND... THE ETA IS
NOW TRENDING FASTER WITH THE SHORT WAVE MOVING FROM THE
PAC NW AT 36 HRS TO UPR MS VLY BY 60 HRS. FINALLY... THE ETA IS
TRENDING LEFT WITH HURRICANE IVAN OR A MORE WNW TRACK.

GFS...
THE 12Z GFS IS VERY COMPARABLE TO THE 00Z/08 GFS EXCEPT ON
TWO FRONTS. THE 12Z GFS IS TRENDING STRONGER AND MORE
AMPLIFIED WITH THE SHORT WAVE TROUGH MOVING INTO THE NRN
PLAINS BY 60 HRS. ALSO... THE 12Z GFS IS TRENDING LEFT WITH THE
FUTURE OF HURRICANE IVAN... BY 60 HRS NOW NEAR ERN JAMAICA.

MODEL DIFFERENCES AND PREFERENCES...

THE 12Z MODEL GUIDANCE SHOW A NUMBER OF DIFFERENCES DURING
THE 60 HR FCST PERIOD.

CONCERNING TD FRANCES... THE MODELS ARE IN VERY GOOD
AGREEMENT OVER THE FIRST 36 HRS WITH A TRANSITION FROM THE
SRN APPALACHIANS INTO NRN NEW YORK STATE. BY 48 HRS... THE
CANADIAN/GFS PROGRESS THE SURFACE WAVE MORE DOWNSTREAM
WHILE THE ETA/UKMET ARE A BIT SLOWER AND A POSITION AT 48 HRS
JUST NORTH OF NRN ME. THE ETA AND UKMET ARE MORE
CONSOLIDATED WITH THE SURFACE LOW WHILE THE GFS AND
CANADIAN ARE MORE ELONGATED WITH THE LOW PRESSURE AREA.
HPC SUGGESTS USING A BLEND THROUGHOUT THE FCST WITH TD
FRANCES.

CONCERNING THE SHORT WAVE TROUGH MOVING INTO THE NRN
PLAINS BY 60 HRS... THE 12Z MODELS ARE DECENT WITH THE
AMPLIFICATION OF THE TROUGH BUT DIFFER SLIGHTLY ON THE
PROGRESSION AND SPEED OF THE UPPER-LEVEL DYNAMICS. THE
ETA/GFS AND UKMET ALL PRETTY MUCH HAVE THE UPPER TROUGH
AXIS OVER THE NRN PLAINS BY 60 HRS WITH THE CANADIAN BEING
MUCH SLOWER... JUST EXITING THE NRN ROCKIES. SENSIBLE WEATHER
WITH THIS FEATURE WILL BE MINIMAL AND SUGGEST FOLLOWING THE
CONSENSUS OF THE ETA/GFS AND UKMET.

CONCERNING THE RATHER AMPLIFIED UPPER TROUGH APPROACHING
THE PAC NW AT THE END OF THE PERIOD... THE GFS AND UKMET ARE
MORE PROGRESSIVE IN MOVING THE SURFACE COLD FRONT AND
BROAD ONSHORE FLOW INTO NWRN WA BY 60 HRS. THE ETA IS JUST A
TAD SLOWER IN DOING SO... WHILE THE CANADIAN IS MUCH SLOWER.
SUGGEST LEANING TOWARD THE GFS/UKMET HERE WITH THE UPPER
TROUGH AND SURFACE COLD FRONT.

CONCERNING THE FUTURE OF HURRICANE IVAN... THE ETA/GFS AND
UKMET ALL HAVE A POSITION AT 60 HRS SOMEWHAT NEAR JAMAICA.
THE ETA AND GFS TRENDED LEFT WITH ITS PREVIOUS TRACK... WHILE
THE UKMET IS VERY CONSISTENT. THE CANADIAN SOLUTION IS MORE
PROGRESSIVE MOVING THE TROPICAL CYCLONE DOWNSTREAM AND
JUST SOUTHWEST OF THE CAYMAN ISLANDS AT 60 HRS. THE CANADIAN
MODEL HAS BEEN THE MOST CONSISTENT MODEL OVER THE PAST 24
HRS WITH IVAN AND FOLLOWS MUCH MORE CLOSER TO CLIMATOLOGY.
HPC STRONGLY SUGGESTS FOLLOWING THE OFFICIAL TPC FCST
CONCERNING HURRICANE IVAN.

MUSHER

MODEL BIASES AT http://WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML