18:00 Tropical models=BAMM and BAMD differ from UKMET

[cycloneye]

NATIONAL HURRICANE CENTER NORTH ATLANTIC OBJECTIVE AIDS FOR

HURRICANE IVAN (AL092004) ON 20040906 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
040906 1800 040907 0600 040907 1800 040908 0600

LAT LON LAT LON LAT LON LAT LON
BAMD 11.4N 54.4W 12.2N 57.3W 13.1N 60.2W 14.2N 63.0W
BAMM 11.4N 54.4W 12.2N 57.5W 13.1N 60.5W 14.2N 63.4W
A98E 11.4N 54.4W 12.5N 57.9W 13.3N 61.2W 13.8N 64.1W
LBAR 11.4N 54.4W 12.2N 57.8W 12.9N 61.4W 13.7N 65.1W
SHIP 100KTS 103KTS 111KTS 115KTS
DSHP 100KTS 103KTS 111KTS 115KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
040908 1800 040909 1800 040910 1800 040911 1800

LAT LON LAT LON LAT LON LAT LON
BAMD 15.5N 65.6W 17.7N 69.8W 19.2N 72.3W 20.9N 73.4W
BAMM 15.6N 66.2W 18.2N 70.7W 20.3N 73.9W 22.4N 75.9W
A98E 14.0N 66.7W 15.2N 71.1W 16.2N 74.8W 17.7N 78.0W
LBAR 15.0N 68.7W 17.3N 74.3W 17.9N 77.0W 20.5N 77.6W
SHIP 118KTS 118KTS 118KTS 117KTS
DSHP 118KTS 110KTS 71KTS 70KTS

...INITIAL CONDITIONS...
LATCUR = 11.4N LONCUR = 54.4W DIRCUR = 285DEG SPDCUR = 19KT
LATM12 = 10.8N LONM12 = 50.5W DIRM12 = 276DEG SPDM12 = 20KT
LATM24 = 10.2N LONM24 = 46.8W
WNDCUR = 100KT RMAXWD = 15NM WNDM12 = 110KT
CENPRS = 969MB OUTPRS = 1010MB OUTRAD = 200NM SDEPTH = D
RD34NE = 120NM RD34SE = 90NM RD34SW = 50NM RD34NW = 100NM

Grafic below that shows the BAMM and BAMD models not in agreement with UKMET as they go more closer to Florida than the UK which goes to the northern tip of the Yucatan.



http://www.sfwmd.gov/org/omd/ops/weathe ... orm_09.gif

[Brent]

[wxman57]

A reminder - the BAM models are not dynamic. They don't use physics to calculate flow pattern changes. They just remove the hurricane from the current flow pattern and make the assumption that the winds upstream will not change in 5 days. That works OK south of 20N where fronts/trofs don't dip down, but not so well when the weather pattern is changing - like with the weakness in the ridge now over Florida. The BAMM/BAMD assume it's there forever.