[Update 9:30P MDT]:
One major update among the range of updated information is available tonight. Forecasts are notoriously difficult for hurricanes. Ike exploded in the past eight hours. More details on him below. As usual, the updates are alphabetical.
Tropical Depression Gustav remains stuck over eastern Oklahoma/western Arkansas. There hasn’t been any change to his future.
Tropical Storm Hanna has maintained herself quite nicely in the face of very unfavorable environmental conditions. Her vitals include: center located at 23.2N, 72.1W; maximum sustained winds of 65mph; moving NNW @ 12mph; minimum pressure of 989mb. So Hanna has begun moving just west of north. Her path should move a little more west in the next day and continue thereafter.
There is some distance between Hanna and the Bahama Islands. They’re not experiencing drenching rains so much as they’re seeing winds just under tropical storm strength that get gusty at times and the surf is getting kicked up a bit. The official intensity forecast calls for Hanna to reintensify to hurricane strength by Friday morning. As you’ll read below, her intensity could jump up unexpectedly as she moves over warmer, but shallower, waters on her way toward the U.S. By Friday night, Hanna should be located off the coast of South Carolina. The next day’s worth of motion and investigation will really affect her exact path and potential landfall sites.
Somewhere near this same time, she should once again shift her trajectory back toward the north, then the northeast. This could keep her from making landfall over South Carolina and instead do so over eastern North Carolina. The official track forecast still keeps Hanna close to either the ocean or the shore, depending upon the eventual track. Regardless, she looks likely to affect a lot of square miles as she makes her way northeast from North Carolina, possibly getting up toward New Jersey by Saturday night as a Tropical Storm.
Hanna should continue to make her way around the periphery of the high pressure system responsible for her steering. She could affect the remainder of the New England region and southeastern Canada before she moves away from land around 50N by next Monday.
Okay – the big news of the day. Tropical Storm Ike became Hurricane Ike earlier this afternoon. Since then, his intensity has simply exploded. Hurricane Ike is now the third major hurricane of the 2008 Atlantic season. In fact, Ike blew through Categories 2 and 3. He is now a Category 4 storm! Here are his vitals as of tonight:
Center located at 22.1N, 54.1W; maximum sustained winds of 135mph!; moving WNW @ 17mph; minimum pressure of 948mb!! I’ll look for the official measurement, but it seems to me like Ike’s pressure dropped 36mb in about 6 hours. That is incredible intensification and is indicative of the massive heat content available in the Atlantic Ocean. Beneficial environmental conditions haven’t hurt him any, obviously. Ike still has a very small, tight eye on satellite imagery. Additional intensification is possible in the next 12 hours, but any further changes will be dependent on eye-wall replacement cycles.
In between 12 and 72 hours (.5 – 3 days), Hurricane Ike will experience northeasterly shear as the upper level low that was affecting Hanna makes its way eastward across the Atlantic. The official intensity forecast calls for slight weakening during that time period. Ike’s official track forecast calls for him to continue his general northwestward motion over the next 24-36 hours. Starting Friday morning, Ike should curve back toward the southwest as a ridge restrengthens after the low passes through the region. Ike should pass well north of Puerto Rico Friday night through Saturday morning. Saturday night could see Ike north of the Dominican Republic, again at a good distance.
The ridge that should push Ike southward in the 2-4 day time period should shift around late day 4 and then in day 5 as well. Similar to Hanna’s track around the ridge, Ike should move around the southwestern periphery of the same feature. That means Ike could move through the southern portion of the Bahamas (not much change from earlier) on his way through the central Islands by the time Monday night rolls around. During the 4-5 day time period, the official forecast calls for Ike to reintensify back to a Category 4 storm.
So starting at the beginning of next week, things are going to get exciting for the U.S. Will Ike make landfall over Cuba? Will he make landfall over the U.S.? Will he move through the Florida strait into the Gulf of Mexico? If he makes landfall over the U.S., where will that occur? Will he follow Hanna’s path around the edge of the ridge and possibly miss land altogether? Also of importance: Hanna has stirred up the Atlantic around the Bahamas for quite some time now. Ike could encounter much cooler surface waters than Hanna had available to her. Will that work to weaken Ike somewhat or quite a bit? There are lots of questions. We’ll just have to keep watching.
Tropical Storm Josephine’s future hasn’t changed since this afternoon. Let’s start with her current vitals: center located at 13.9N, 30.7W; maximum sustained winds of 50mph; moving W @ 12mph; minimum pressure of 1000mb. Josephine is still forecasted to begin moving more north of west in the next couple of days, albeit a little more slowly than her current speed. She is still forecasted to weaken to Tropical Depression status by Saturday, if not sooner.
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[Update 4:00P MDT]:
Tropical Depression Gustav continues to spin away while over Arkansas. Some precipitation totals from the storm are truly impressive: over 10″ at a number of sites and over 19″ at one! He is still expected to be caught up in the large-scale flow in 2-3 days.
Tropical Storm Hanna has definitely started moving north in response to the upper-level low moving away to the east. As that situation unfolds, the shear impacting Hanna should gradually lessen. Her vitals:
Centered at 21.9N, 71.9W; maximum sustained winds of 60mph; moving N @ 12mph; minimum central pressure of 989mb.
Hanna is still forecasted to turn toward the northwest during the next few days, moving along side the Bahama Islands before threatening the U.S. later in the forecast period. Now that her center has been more confidently pinpointed and she has begun clearly moving again, the official track forecast has been adjusted. The model suite has shifted toward the east since this morning’s runs. The official forecast calls for Hanna to make landfall along North Carolina’s coast, perhaps between Wilmington and Jacksonville, sometime on Saturday. Given the large uncertainty involved in the track forecasts recently, it is best to wait a little while longer before calling the specific location. Given this latest official track, Hanna could just as easily remain out to sea. As I wrote this morning, Hanna is going to produce high surge and moderate waves. Beaches up and down the coast are going to be affected. Hanna could intensify to a Category 1 hurricane, or it could just as easily maintain her tropical storm status.
Tropical Storm Ike has intensified to Hurricane Ike, as forecasted earlier today. His updated vitals:
Center located at 21.6N, 52.7W; maximum sustained winds of 80mph; moving WNW @ 18mph; minimum pressure of 984mb.
Ike has a nice, tight eye that developed during the day. Outflow looks alright over the entire storm, and he is displaying very cold cloud tops in the northeast quadrant. His future has shifted slightly during the day as well. Interactions with the upper-level low that is leaving Hanna behind and the eventual restrengthening of the ridge currently providing steering will provide an interesting path across the basin. Ike is expected to keep intensifying over the next 24 hours, possibly to a Category 2 storm, before the low introduces some shear. Some weakening should occur in the 1-2 day time period, after which Ike should reintensify as he encounters even warmer ocean waters and very little vertical shear. Between Friday night and Saturday afternoon, Ike is forecasted to restrengthen to a Category 2 storm. Starting early Friday morning, Ike should shift direction from WNW to WSW as the ridge strengthens to his north.
During the day on Sunday, Ike could continue intensifying to a Category 3 storm. During Sunday afternoon or evening, Ike could begin moving WNW again as the ridge providing steering shifts around. This means the Bahamas could experience another major hurricane as Ike passes through the southern to central Islands Sunday through Monday. That’s the official forecast. It is important to understand that the suite of models all agree on the general pattern described above, but the exact placement and strength of the storm, especially more than three days from now, is very uncertain. A Hispanola landfall or staying out in the Atlantic the entire period are still valid possibilities.
Tropical Storm Josephine has weakened today as dry air and shear interrupt her flow. Her vitals this afternoon:
Center located at 13.8N, 29.9W; maximum sustained winds of 60mph; moving W @ 13mph; minimum pressure near 997mb.
Josephine is forecasted to continue to battle shear over the next 3 days. Her ability to maintain convection and organization will affect her track. She is officially expected to move toward the west across the basin. Less movement northward is now forecasted. If the shear and future cooler surface temperatures do too much, Josephine could weaken back to a Tropical Depression, and that’s what the official forecast calls for Saturday night or Sunday morning.
Not that we need another system to keep an eye out for, but given Josephine’s current position and the general spacing of disturbances across Africa, another disturbance should make its way off Africa in the next day or so. The Atlantic season doesn’t peak climatologically until Sep. 10th.
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There hasn’t been much change since yesterday with respect to the number of storms, their current characteristics or their futures. Alphabetically:
Tropical Depression Gustav remains pretty stationary over northeastern Texas/southwestern Arkansas. He is still pulling Gulf moisture north and west around the central remnant low. He is forecasted to become extratropical in the next 48 hours, moving NNE, then NE over the next 3-4 days.
Tropical Storm Hanna has nearly completed a loop between the Bahamas and Hispanola. Her vitals:
Center located near 20.6N, 71.8W; maximum sustained winds of 60mph; moving N @ 6mph (finally, some movement); minimum pressure of 997mb (significantly higher than yesterday).
Hanna has really battled some adverse environmental conditions over the past four days. Her center is ill-defined today as she interacts with the moving upper-level low to her north. Things should improve over the next 24-48 hours as she finally begins her northwestward treck. Her official track forecast should take her along the eastern coasts of the Bahama Islands. By Friday, she should be east of Florida (and the Bahamas still), and could restrengthen back to hurricane status. She is expected to really pick up speed on Friday, and could be off the coast of South Carolina by Saturday morning. The eventual landfall is currently expected to occur near Georgetown, SC by Saturday afternoon.
Given Hanna’s forecasted path toward South Carolina and the orientation of the SC coast to the storm, storm surge will likely be a problem south of North Island, which means it would definitely affect Charleston. All the beaches along the SC coast will have to deal with high surge and moderate-sized waves.
It looks as though Hanna’s loop in the Atlantic has shifted her entire forecasted path toward the east. She could come back out across the Atlantic off Virginia later in the day Saturday, then make an additional landfall in the Massachusetts/Rhode Island area Sunday morning as a Tropical Storm, skip out to the Atlantic again, then impact Newfoundland Sunday night or Monday morning. Her curving path could parallel pretty much the entire eastern seaboard.
Tropical Storm Ike’s future got more interesting this morning. He has got some banding features starting to become visible. Microwave satellite imagery indicated a nascent eye, which means Ike could display a visible eye before the day is out. Here are Ike’s vitals this morning:
Center located near 20.8N, 51.2W; maximum sustained winds of 70mph; moving WNW @ 18mph (Ike is still moving quite rapidly across the Atlantic); minimum pressure near 991mb.
Ike is expected to strengthen to a Category 1 hurricane later today. He is passing over warm waters (warmer with every mile traveled) and has little shear to deal with. That shear is expected to increase in the next couple of days as the upper-level low currently tamping down Hanna moves east across the Atlantic. Ike should maintain his hurricane status during this interaction, however. His motion is officially forecasted to shift a little more northward over the next 2-3 days, after which it is forecasted to move south of west in the 4-5 day time period.
Ike is expected to be a Category 1 hurricane come Saturday morning, when he is forecasted to be north of Puerto Rico (by a good distance). After that, steady intensification is forecasted by intensity models. By early morning Sunday, Ike could be passing over the southern Bahamas as a Category 2 storm. By early morning Monday next week, Ike could be impacting the central/western Bahamas as a Category 3 (a major hurricane).
I would like to note at this time that the forecast track envelope is considerably wider in the extended days than it was yesterday. The UKMET pulls Ike up past 25N and even close to 30N by day 5. The NGFDL and GFDL models indicate a Hispanola landfall (south of 20N) on Saturday. The official forecast keeps Ike near the center of the envelope.
Tropical Storm Josephine hasn’t changed much since last night. She is exhibiting some weak banding features, but her infrared satellite signature remains unimpressive. Her vitals:
Center located near 13.8N, 28.8W; maximum sustained winds of 65mph; moving W @ 10mph; minimum pressure of 994mb.
T.S. Josephine will continue moving across the Atlantic and remain well away from any landmasses. All of the model track forecasts indicate she will begin moving north of west during the forecast period. Come to think of it, they’ve indicated this movement for a day now and it hasn’t really happened yet. Josephine has moved steadily westward so far. In any event, she could move north of 15N sometime tomorrow and north of 20N sometime Sunday. During the five day period, she isn’t expected to intensify to hurricane strength. In fact, environmental conditions look worse in her future and the NHC is calling for her to gradually weaken in the five day forecast period.
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