For an update on Tropical Depression Ida as it came off the Honduran Coast, CLICK HERE
Tropical Storm Ida became Hurricane Ida before making landfall and spent the day over Nicaragua. In the process found itself downgraded to a Tropical Depression. Initial reports are the winds caused some damage but officials are concerned about the potential for up to 20 inches of rain to fall in Nicaragua and Honduras before Ida leaves town. The official Ida forecast track from the National Hurricane Center calls for it to trudge across Honduras for the better part of Friday before emerging late in the day just off the northeast coast of that country. The center of circulation is close enough to the water that perhaps it will be able to maintain its integrity sufficiently to allow it to regenerate somewhat once its back over water. That is what the official forecast calls for as it takes the storm through the Yucatan Channel and into the Gulf of Mexico.
Now, as I mentioned yesterday, some of the models didn’t really give the cold front coming down too much credit but the spaghetti model indicates that several are now reflecting the cold front’s presence as toward the latter part of the extended tracks, you see it beginning to veer to the right. Part of that is due to coriolis forces but much of that is a reflection of a breakdown the Caribbean ridge that has been steering the storm north as the cold front approaches. The National Hurricane Center forecast reflects that kind of thinking and, you know what, it makes sense. As long as the front behaves and gets into the Gulf by Tuesday, then the storm will begin to curve. But, if the front is behind schedule, then that turn may not take place until it does. Most data indicates that, regardless of the frontal timing, the associated trof should be deep enough to the south to pick up the storm and when it does, look for Ida to accelerate to the northeast. One thing of interest. If you look at the Total Precipitable Water loop to the left, two things stand out. First is how subtle the circulation of Ida was as it developed off the coast. Second, note all of the extremely dry air being pushed down from North America and how far that extends into the Gulf.
I would think a plausible scenario would be for the storm to move into the big bend of Florida and exit into the Atlantic somewhere between Daytona and Savannah. But, there are many variables, not the least of which is getting Ida out of Central America in tact and then have it be in an environment to redevelop. Those are both formidable “ifs” but most data suggests that is what will happen. However, only 3 of 17 models that make up the 00z spaghetti model intensity run take Ida back up to Hurricane status. The NHC discussion below addresses the intensity issues.
WTNT41 KNHC 060241
TROPICAL DEPRESSION IDA DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112009
1000 PM EST THU NOV 05 2009
SURFACE OBSERVATIONS AND CONVENTIONAL SATELLITE IMAGERY INDICATE
THAT IDA HAS WEAKENED TO A TROPICAL DEPRESSION. WHAT REMAINS OF THE
DIMINISHING DEEP CONVECTION IS CURRENTLY CONFINED TO NORTHWEST AND
NORTHEAST QUADRANTS. SOME FURTHER WEAKENING IS LIKELY DURING THE
NEXT 12 TO 24 HOURS AS IDA CONTINUES ON A GENERAL NORTHWARD TRACK
OVER NORTHEASTERN NICARAGUA AND EASTERN HONDURAS. AROUND THE 36
HOUR PERIOD…THE CYCLONE SHOULD EMERGE OVER THE NORTHWEST
CARIBBEAN SEA AND…ASSUMING THE CIRCULATION IS NOT TOO SEVERELY
DISRUPTED BY ITS PASSAGE OVER LAND…THE SYSTEM SHOULD RESTRENGTHEN
INTO A TROPICAL STORM. HOWEVER…THE GLOBAL MODELS INDICATE ONLY A
MARGINALLY FAVORABLE UPPER-LEVEL WIND ENVIRONMENT OVER THE
REGION…WHICH SHOULD CURTAIL SIGNIFICANT INTENSIFICATION AS IDA
HEADS IN THE GENERAL DIRECTION OF THE YUCATAN CHANNEL. AFTER IDA
ENTERS THE SOUTHERN GULF OF MEXICO….THE INTENSITY FORECAST IS
HIGHLY UNCERTAIN. THE LARGE-SCALE MODELS ALL AGREE ON AN
INCREASINGLY STRONG VERTICAL SHEAR ENVIRONMENT DEVELOPING OVER THE
GULF OF MEXICO TOWARD THE END OF THE FORECAST PERIOD. THE GFDL AND
HWRF MODELS…PARTICULARLY THE FORMER…SHOW SIGNIFICANT
INTENSIFICATION OF IDA IN THE LATTER PART OF THE PERIOD. IT SHOULD
BE RECALLED HOWEVER THAT THESE MODELS HAVE BEEN KNOWN TO HAVE A
HIGH BIAS IN STRONGLY SHEARED ENVIRONMENTS…AS WAS THE CASE WITH
TROPICAL STORMS DANNY…ERIKA…AND HENRI OF THIS YEAR.
CONSEQUENTLY…THE OFFICIAL WIND SPEED FORECAST LEANS MORE TOWARD
THE WEAKER LGEM AND SHIPS PREDICTIONS.
THE INITIAL MOTION IS ESTIMATED TO BE 330/4…WITHIN THE SOUTHERLY
STEERING FLOW ON THE WEST SIDE OF A WEAK MID-LEVEL RIDGE. WITH THE
EXCEPTION OF FORWARD SPEED DISPARITIES…THE GLOBAL AND REGIONAL
MODELS CONTINUE TO INDICATE A GENERAL NORTH TO NORTH-NORTHWESTWARD
MOTION INTO THE CENTRAL GULF OF MEXICO OVER THE NEXT 4 DAYS.
AROUND THE END OF THE PERIOD…MOST OF THE TRACK GUIDANCE SHOWS A
TURN TO THE RIGHT AS IDA BEGINS TO INTERACT WITH THE WESTERLIES.
THE OFFICIAL FORECAST HAS CHANGED LITTLE FROM THE PREVIOUS ONE AND
IS CLOSE TO THE MODEL CONSENSUS.
THE BIGGEST IMPACT OF THIS SLOW-MOVING SYSTEM DURING THE NEXT DAY OR
SO WILL LIKELY BE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES
CAUSED BY EXTREMELY HEAVY RAIN OVER PORTIONS OF NICARAGUA AND
FORECAST POSITIONS AND MAX WINDS
INITIAL 06/0300Z 13.8N 84.1W 30 KT
12HR VT 06/1200Z 14.4N 84.1W 25 KT…INLAND
24HR VT 07/0000Z 15.4N 84.2W 25 KT…INLAND
36HR VT 07/1200Z 16.6N 84.5W 35 KT…OVER WATER
48HR VT 08/0000Z 17.7N 85.0W 40 KT
72HR VT 09/0000Z 20.3N 86.2W 45 KT
96HR VT 10/0000Z 23.0N 87.5W 45 KT
120HR VT 11/0000Z 26.0N 87.0W 45 KT