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Posted at 12:00 PM ET, 09/ 2/2008

Could Hanna Hit D.C. Hard?

By Jason Samenow

Struggling storm downgraded but may recover

hanna-track.gif
National Hurricane Center track forecast for Hanna. The current track takes Hanna right over Washington, D.C.

The 2008 tropical season, like a gifted quarterback, is spreading the action all over the playing field -- in this case the U.S. Gulf and East Coast. Dolly socked southern Texas, Fay flooded Florida, Gustav engulfed Louisiana, and now Hanna may pound the Southeast Coast. Computer models are almost unanimous in bringing Hanna ashore in Georgia or South Carolina early Friday. Then it will race northward. Depending on Hanna's exact path on its journey north and its intensity, the D.C. metro region may feel a powerful blow.

It should be noted, however, that Hanna is battling powerful wind shear today which is ripping apart its structure. It was recently downgraded to a tropical storm. The shear is forecast to weaken allowing Hanna to recover, but there is a small possibility it will not -- which would all but end the threat of significant impacts along the East Coast.

Keep reading for more on the potential impacts of Hanna on the D.C. area. See also our full forecast through the weekend.

Assuming Hanna survives, it has the potential to be a significant rain producer. Last night, the National Weather Service office in Sterling was bullish about the prospects for meaningful rain:

AT MINIMUM...HANNA WILL BRING RAINFALL TO THE FORECAST AREA BEGINNING SOMETIME FRIDAY AND LINGER THROUGH AT LEAST PART OF THE WEEKEND.

rainfall-potential-0902-0z.gif
Rainfall potential from Hanna. Courtesy NOAA.

How much rain? NOAA's Hydrometeorological Prediction Center indicates the potential for 4-5" of rain although that number will be highly dependent on the storm's track. If Hanna tracks west of the mountains, the metro area might just experience intermittent showers from the outer bands and less than 2". If the center passes very close to us and we experience torrential downpours associated with the storm's core, some locations could receive more than 5" and flash flooding. Having said that, Hanna will likely be a fast mover, which should limit rainfall amounts to an extent. The exact timing of Hanna's arrival and departure can't yet be pinned down. But early indicators suggest the time of impact may be late Friday into early Saturday.

As for wind, the Sterling NWS was pretty vague:

THE WIND FORECAST IS HIGHLY UNCERTAIN...AND COMPLETELY DEPENDENT ON THE TRACK...TIMING AND INTENSITY OF HANNA.

I'll fill in some detail here. The National Hurricane Center predicts Hanna will come ashore as a Category 1 storm with winds to 85 mph, but as with Gustav and most tropical weather systems, this forecast is highly uncertain. Last night, AccuWeather's Joe Bastardi suggested it could make landfall as a Category 3 storm. Water temperatures are pretty warm off the Southeast coast and wind shear, ripping Hanna apart at present, is forecast to relax as the storm approaches the coast.

Suffice to say, if Hanna strikes South Carolina as a hurricane and races northward through the metro region, we could experience tropical storm winds as in Isabel of 2003.

If the storm tracks well to our west and the center of the storm is over the mountains, we may not experience these strong sustained winds. However, locations east of land-falling hurricanes often experience severe thunderstorms and possible tornadoes embedded within the storm's outer bands. Some of you may recall the when the remnants of Hurricane Ivan spawned a record 40 tornadoes in Virginia in September, 2004.

The other major impact we will need to monitor is the potential for storm surge. If the storm tracks just west of the Chesapeake Bay, a tidal surge may be pushed up the Bay producing a flooding along the shores of the Potomac as in Isabel or the Chesapeake-Potomac hurricane of 1933, which we recently profiled on its 75th anniversary.

Obviously, there are a lot of possibilities with this storm but it does appear to have some potential to have significant impacts on the metro area. There is a chance that it may track far enough west that we dodge the bullet a la Hurricane Hugo in 1993. Or, it could pass far enough east that we only receive a glancing blow a la Gloria in 1985. Or, it may fizzle out and not impact anyone. Time will tell.

We will provide frequent updates as this storm possibly approaches the East Coast in the coming days. Track Hanna, Ike, and several other disturbances using the tracking map below.

Powered by hurricane-tracking software from Stormpulse.com. Pan, zoom, and click on points along the storm's projected track for intensity forecasts.

By Jason Samenow  | September 2, 2008; 12:00 PM ET
Categories:  Tropical Weather  
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Comments

If I'm reading that Hannah graphic correctly, the famous GFDL model takes it pretty far west of D.C.

Posted by: jmbethesda | September 2, 2008 12:17 PM | Report abuse

TS Josephine has joined the party:
http://www.nhc.noaa.gov/refresh/graphics_at5+shtml/144814.shtml?5day#contents

Lined up like jets on a runway, aren't they?

Posted by: D.K. in Alex/Mt. Vernon | September 2, 2008 1:08 PM | Report abuse

Does anyone know when the most names storms at one time were in the Atlantic basin?

Posted by: D.K. in Alex/Mt. Vernon | September 2, 2008 1:12 PM | Report abuse

Nice compilation Jason, the software from stormpulse is pretty sweet! I'd have no problem with a rainy, stormy weekend, minus the 5 days of no power ala Isabel!

Posted by: Mike from the Blue Ridge | September 2, 2008 1:22 PM | Report abuse

The last time that we had 4 named in the Atlantic was September of 1998, Georges, Ivan, Jeanne and Karl. This is also the record for most storms at one time. Currently though, we can't count Gustav, as the NHC has stopped its advisories. So technically, we only have Hannah, Ike, and Josephine.

Posted by: Brian, Capital Weather Gang | September 2, 2008 1:57 PM | Report abuse

Bring it on! I love storms.

Posted by: Havoc | September 2, 2008 1:57 PM | Report abuse

Hoping that the weather settles a little for my wedding next Saturday!

Posted by: Kalorama Park | September 2, 2008 2:25 PM | Report abuse

I recall almost being a victim of a tornado spawned by the remnants of Hurricane Opal in 1995 as it moved north- northeast from the Gulf through central Kentucky and Ohio. (http://en.wikipedia.org/wiki/Hurricane_Opal)

I had been sitting in my car waiting to pull out from a parking lot in Camp Springs, MD. It was after dark with what appeared to be a totally overcast sky and not raining. I thought at the time Opal's track several hundred miles to the west presented no threat - nor had any been offered officially or otherwise.

Yeah, perhaps I should have known better, but .... Anyhow, as I was waiting, the wind rapidly and unexpectedly picked up to the point my car was shaking and actually lifted straight up a couple feet.

Fortunately, the winds subsided as rapidly as they had begun, and I escaped without injury or damage to my car.

Within 100 yards, damage was extensive to houses, power lines, trees, etc. No life threatening injuries were reported. As fortunate as I was, this (as later reported) F1 tornado just missed the crowded indoor swimming facility that I was just leaving

This was the only tornado I'd ever experienced first hand. And gee, it was so dark, I never got to see it - approach or depart the scene.

Posted by: Steve Tracton | September 2, 2008 4:05 PM | Report abuse

Yep, Isabel was bad west of D.C. Tore the roof off a neighbor's house in Harpers Ferry. I was in D.C. for it. Interesting experience, driving around a virtually deserted city. I could almost see where I was going through the horizontal rain.

Posted by: tinkerbelle | September 2, 2008 4:33 PM | Report abuse

Great. I was up in DC while the folks back home were getting absolutely pounded back in SC during Hugo. My parents' place had trees lying down around it like some giant was playing pick up sticks. And now I fly up to DC this morning for meetings today through Thursday. . .Hanna better give them a miss if I can't make it home.

Posted by: Lowcountry Guy | September 2, 2008 4:42 PM | Report abuse

So. Now that everybody has gotten me scared (oh yeah and still very excited) about the potential fallout of a TS in DC, I have a question.

Would I be like one of those crazy people who buy water and toilet paper before a 1" snowstorm if I go to the store tonight and buy some extra water and nonperishable food in case we lose power for a few days?

What do you think...does Hanna have the potential to knock out the power for a significant amount of time? (I know this is a guess at this point...but guesses are fun.)

Posted by: Laura in NWDC | September 2, 2008 5:55 PM | Report abuse

Currently Hanna is struggling, and actually moving SSE back toward Haiti. It may lose some projected strength even if it does move N. In the event we get rain it may last only ca. 6 hr. due to rapid movement of the storm. It all may be out of here by 6 PM Saturday, according to some projections.

In the event Hanna tracks quite a few miles to our W, we'll see less rain, but probably more thunderstorms and possible tornadoes [cf. Ivan, as noted]. This is currently happening E of Gustav in LA and MS.

It's too early at this stage to forecast Ike or Josephine, but Ike could threaten the continental U.S.

Posted by: El Bombo | September 2, 2008 6:14 PM | Report abuse

Laura in NWDC: I don't think it's ever wrong to be prepared. If Hanna doesn't hit, you'll have the supplies for a future storm, be it hurricane or blizzard. No harm in getting things in advance, so go when it's convenient for you.

Posted by: ~sg | September 2, 2008 6:26 PM | Report abuse

What a story, Steve! If you go online, you can even see a video of tornado formation just feet from the in-car cameraperson.

Posted by: mcleaNed | September 2, 2008 7:53 PM | Report abuse

The comments to this entry are closed.

 
 
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