Ike trying to restrengthen (updated at 11 PM Friday)
September 5, 2008
(Updates in italics, CAPS indicate a quote from the 11 PM NHC forecast discussion)
At this time two days ago, Hurricane Ike unxepectedly started to strengthen rapidly and peaked with 145 mph winds on Thursday morning. From then on unfavorable upper-level winds took weakened the storm. Data from the Hurricane Hunter collected mid-afternoon supported winds of 115 mph, a minimal category three. Since then satellite imagery is starting to show an eye again, something that hasn’t been visible today (see infrared loop, also compare this morning with this evening).
THE EYE OF IKE BRIEFLY RE-APPEARED AROUND 0000 UTC. SINCE THAT TIME AN INTERMITTENT WARM SPOT HAS BEEN SEEN IN THE CENTRAL DENSE OVERCAST IN CONVENTIONAL SATELLITE IMAGERY. THE LATEST MICROWAVE IMAGERY FROM JUST PRIOR TO 0000 UTC INDICATED THAT THE EYE HAD A SMALL OPENING IN THE NORTHWESTERN QUADRANT
Ike still has challenges ahead of it in the short term (next 36-48 hours). The shear analysis suggests that Ike is in the local minimum as far as shear goes, but is facing an increase as it continues west (although models suggest that’s only true for the next 24 hours or so). As far as drawing energy from the ocean goes, Hanna’s stay in the area has given Ike a bit of a handicap. A comparision with heat content a week ago with heat content today indicates that Hanna stole some potential fuel from Ike. However, loooking further west, there is plenty of heat for Ike to tap into.
THE NORTHEASTERLY SHEAR CURRENTLY DISRUPTING THE HURRICANE IS FORECAST TO ABATE DURING THE NEXT 12 TO 24 HOURS. SINCE IKE...STILL APPEARS TO BE A VERY HEALTHY HURRICANE...LITTLE IF ANY ADDITIONAL WEAKENING IS EXPECTED BEFORE IT REACHES THE SOUTHEASTERN BAHAMAS. BEYOND 36 HOURS...THE SHEAR IS FORECAST TO BE VERY LIGHT AND THE ONLY NEGATIVE FACTOR FOR STRENGTHENING WILL BE POSSIBLE LAND INTERACTION.
These conditions are reflected in the current intensity forecast, which brings Ike down slightly to 110 mph. (That could eliminated in the 11 PM advisory if the satellite imagery continues to suggest strengthening. However, due to the reconnaissance flights focusing on Hanna, we won’t have a plane to verify anything until 2 AM). (That was the case as satellite estimates were between 115 and 130 mph, see below) After that, Ike is predicted to get back up to 135 mph winds.
SUBJECTIVE AND OBJECTIVE DVORAK INTENSITY ESTIMATES ARE BETWEEN T5.5 AND 6.0... AND THE ADVISORY INTENSITY WILL REMAIN 100 KT...OR AT THE LOWER END OF THOSE ESTIMATES. ANOTHER AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE IKE AROUND 0600 UTC...WHICH SHOULD PROVIDE A MORE ACCURATE ASSESSMENT OF IKE'S STRENGTH.
(0600 UTC = 2 AM EDT)
The wildcard in that is Ike’s track, with the $64 question being whether the storm goes over Cuba. The current forecast (5 PM)says no. The dynamic model guidance from this afternoon, (which shows a suspicious amount of agreement at the 5 day point), shows most models saying no, with the GFDL being a notable exception. The most recent GFDL run is even further south, taking Ike through the Windward Passage, over Gitmo, around the southern coast of Cuba, then turning northwest and crossing the island in a manner similar to Gustav. The most recent HWRF run is also further south. This should cause the official forecast to have a slight adjustment to the south as well (and it did, once again see below as well as the current forecast).
THE TRACK GUIDANCE HAS COME INTO BETTER AGREEMENT ON THIS SOLUTION...AND HAS ONCE AGAIN SHIFTED SOUTH AND WESTWARD. IN FACT...MOST OF THE RELIABLE GUIDANCE NOW TAKES HANNA EITHER OVER OR ALONG THE NORTH COAST OF CUBA. THE NEW TRACK HAS BEEN SHIFTED SOUTH AND WESTWARD OF THE PREVIOUS ADVISORY...AND IT IS ALSO A LITTLE FASTER. IT SHOULD BE NOTED...THAT THE DYNAMICAL MODEL CONSENSUS AND SEVERAL OF THE INDIVIDUAL MODELS ARE SOUTHWEST OF THE 4 AND 5 DAY NHC POSITIONS AND IF THIS TREND CONTINUES SOME ADDITIONAL WESTWARD SHIFT COULD BE REQUIRED.
These southward adjustments are the last thing anyone would want to see for Haiti. While the U.S. has had a run of landfalls, suffering from the storms has been trivial to what has happened in Haiti.
For those in the Keys, especially the lower ones , it is the time to have a plan for leaving (moreso than I realized, tourists are ordered to leave by 8 AM tomorrow and residents are ordered to leave on Sunday). At this point it appears that whether it’s through the front door (from the east) or through the back (via Cuba) Ike will have some affect, possibly severe, come Tuesday.
Looking beyond that, it’s a concern for the eastern half of the Gulf Coast.
When I started to write this post at 7:30 pm or so I started with the title “Ike is strengthening” but by 8:30 I revised it. While an eye was briefly visible, it disappeared again. Also, convection had increased in area, but has since shrunk somewhat. At this point I would expect the Hurricane Hunters to find no change in strength and as such for the 5 am advisory to continue to indicate 115 mph.
Obligations will keep me away from the computer until evening hours tomorrow.