Hanna deepening; Ike forecast in flux

9/6, 11:55 PM EDT: Can’t sleep, so I’ll post a late update on the Atlantic’s tropical trio: Hanna, Ike and Josephine.

Hanna is still a tropical storm as of 11:00 PM EDT, but Charleston radar seems to show a western eyewall trying to form, and the minimum central pressure has dropped to 978 millibars. This would normally signify roughly a borderline Category 1/2 hurricane, though every storm is a little different in terms of the exact relationship between pressure and wind speed. Regardless, the pressure has dropped 3 millibars since 8:00 PM and 6 millibars since 5:00 PM. So Hanna is certainly “deepening.”

Because a storm’s winds often take a few hours to “catch up” to drops in pressure, it wouldn’t be at all surprising to see Hanna’s maximum wind speed ramp up to minimal Cat. 1 hurricane status just before, or even immediately after, landfall — which, incidentally, should take place in 3-6 hours along the northeastern South Carolina coast (in contradiction to my earlier incorrect “midnight” reference; sorry about that). Of course, as the NHC points out, “THERE IS NOT MUCH DIFFERENCE BETWEEN A [70 MPH] TROPICAL STORM AND A [75 MPH] HURRICANE.”

You can follow Hanna’s progress live via this NWS radar loop, which should stay current throughout the night and morning:

See also the Weather Underground radar loops for Charleston, Wilmington and Morehead City.

Jared W. Smith, on his Charleston Weather Blog, writes at 10:34 PM EDT that “Hanna’s made a very sharp jog to the left”:

It’s looking more and more that unless the [predicted] northeast turn happens in the next couple hours from now, landfall will indeed be in northern Charleston County near Awendaw and Bulls Bay. . . . It’s hauling butt . . . As I write this, a squall associated with the inner core of the storm — which is rapidly regenerating — is coming ashore.

With regard to the NHC’s failure to upgrade Hanna to a hurricane, Alan Sullivan writes: “Maybe NHC is getting cautious about these borderline designations, after so many roastings by bloggers.” Heh. Sullivan himself, of course, has been one of the chief “roasters” in that regard. Anyway, he adds: “I see no dramatic wind readings at buoys or coastal stations. Still, Hanna will be an unpleasant experience for people in its path. Very heavy rain is falling in a band just inland and parallel to the coast of South and North Carolina. The intense squalls of the core are about to rake the shoreline near Myrtle Beach. Hunker down!”

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Meanwhile, the 11:00 PM advisory on Hurricane Ike shifts the forecast track to the left — as expected, given the aforeblogged model shift — and the NHC discussion hints that a further leftward shift is possible:

THE TRACK GUIDANCE HAS COME INTO BETTER AGREEMENT . . . 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.

The storm’s trajectory at the end of the five-day forecast period is, it must be said, a bit alarming — not New Orleans again! — but I suspect a sharper turn after 120 hours would be the expectation, leading to a landfall closer to the Florida panhandle. If anything, this might be another Ivan scenario, where the storm seems to take dead aim at N.O. but the forecast insists on a right turn, and we all bite our nails waiting for that predicted turn to happen. But of course, that’s all rampant speculation, as forecasts beyond five days pretty much always are. Bottom line, the whole eastern half of the Gulf coast needs to be watching Ike closely, and at this point, no one particular location is much more at risk for an eventual landfall than any other.

Well, except Key West, which is now in line for a direct hit from a 125 mph hurricane, if the official forecast is correct. That would be, um, bad. I really hope people heed the warnings:

With the potential of Hurricane Ike developing into a dangerous Category 4 storm that hits the Florida Keys, Monroe County authorities are urging everyone to take it seriously and heed evacuation orders issued Friday.

“This is a serious storm,” Key West Police Chief Donie Lee said. “People need to leave.”

Tourists must leave by 8 a.m. Saturday and residents must evacuate on Sunday in phases: by 8 a.m. for Lower Keys residents, noon for the Middle Keys and 4 p.m. for the Upper Keys.

“It sounds like we are at ground zero right now,” Marathon Mayor Pete Worthington said.

National Weather Service Key West office Chief Meteorologist Matt Strahan said people should not be fooled by any apparent weakening in the hurricane because that is expected to be temporary.

“Monroe County residents should not be lulled into a false sense of security,” Strahan said, explaining that Ike’s wind speeds could fluctuate — on Friday it dropped from a Category 4 to a 3 and could drop to a 2 even — but as Hanna pulls away, the hurricane could intensify into a Category 3 or 4 by Sunday.

“As a general rule, you could see your house not just flooded, but washed away if you’re on the right side of the track,” Strahan said. “If you are on the left side, the flooding could be as bad as Wilma. … “It’s a very dangerous storm track. It may look like its declining over the next few days, but it should pick back up.”

Speaking of which, I quote from the NHC discussion again, with regard to the intensity forecast:

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.  WITH THE OFFICIAL TRACK PREDICTION ALONG THE NORTHERN COAST OF CUBA…IT SHOWS ONLY SLIGHT WEAKENING DUE TO LAND.  HOWEVER…IKE COULD BE WEAKER THAN SHOWN BELOW IF THE CENTER MOVES OVER CUBA…AND CONVERSELY COULD BE A LITTLE STRONGER IF IT REMAINS OVER WATER.

Stay tuned, as they say.

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Oh, and if you’re wondering about Josephine — she’s been downgraded to a tropical depression, and advisories may be discontinued soon:

EXCEPT FOR A SMALL BURST OF CONVECTION THAT HAS RECENTLY DEVELOPED ABOUT 120 NM NORTHWEST OF THE CENTER OF JOSEPHINE…THE CYCLONE HAS BEEN UNABLE TO PRODUCE A SIGNIFICANT AREA OF DEEP THUNDERSTORM ACTIVITY FOR WELL OVER 12 HOURS. IN MOST CASES A SYSTEM LIKE THIS WOULD NORMALLY BE DECLARED A REMNANT LOW. SINCE THERE APPEARS TO BE SOME CHANCE FOR RE-STRENGTHENING LATER IN THE FORECAST PERIOD… ADVISORIES WILL BE CONTINUED FOR NOW. ADVISORIES COULD BE DISCONTINUED SOON…BUT COULD ALWAYS BE RESTARTED AGAIN IF THE SYSTEM RE-INTENSIFIES DOWN THE ROAD.