Hanna's Gift: Rain and Rainbows

With the talk of the week come and gone (by the way, I think the forecast and track worked out pretty well), we did get some good things out of the storm.
This Doppler estimated Rainfall shows:
Yellow- Over 1.5 inches
Red - Over 3 inches
Purple- Over 6 inches west side of DC. Tony Pann informed me about numerous water rescues.
More rain fell north and west
Less rain fell around the beltway and the eastern shore...
After a wet spring and summer, August was about 2 inches below normal on rainfall. the 1.64" at BWI made up for some of that and keeps us 3.29" above normal on the year.

BEAUTY How about the rainbows... I did say plural... there was a double rainbow that formed after 7pm and was visible in most spots. Technically everyone sees a different rainbow anyway, I did not want to geek out today. This was most likely the brightest, and best looking natural rainbow I have ever seen. Glad I can a camera handy. Enjoy the pictures (which do not do the full double arch justice). I also have a YouTube video below....

Hanna Visible Satellite in Maryland

Here is the satellite image form around 3pm, showing the center of Tropical Storm Hanna over the lower Chesapeake Bay. At this point, most of the rain was west of Baltimore, while much lighter amounts were closer to the storm center. My morning post is below....
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Hanna: Just the Basics

First Some Weather Cams along the shore:
Ocean City, MD


Rehoboth, DE



Wildwood, NJ



It is going to be a long, busy day... Here are some of the graphics we are working on. The speed had picked up a little this morning, so the timing of the worst part of the storm may begin early to mid aftrernoon. Heavy rain has already developed as of 9am. I have noticed the upslope in the terrain to our north and west has enhanced the rainfall. There could be higher amounts to our west. You can track that in my TV Graphics or Radar tabs above on the main web site.
If I get a chance, I will post a little more later.

Hanna Hits Saturday

I hate, and yet I love these mornings. There is so much to talk about, it all seems like a rush on TV. But that is the benefit of my blog and web site. That is how I can share everything. I am still pressed on time, but I wanted to share as much as possible as soon as possible.
The Track (as of this morning), has Hanna as a Tropical Storm and passing over Salisbury on Saturday evening. The wind field is large with this storm, so the area that will have 40mph winds or higher will be large.
I have included Baltimore in the zone with 40-60mph winds, at least with gusts. On the Bay and the Delmarva- the winds will be holding the full force of the storm, which will likely be steady at 45-65mph on Saturday night.

WATCHES (as of Friday morning)
As of this morning, a Tropical Storm Watch was in effect for the Eastern Shore, Chesapeake Bay, and 'Coastal Areas' of Harford, Baltimore and Anne Arundel Counties. A Flash Flood Watch is in effect for the rest of us.
Basically, we all will get something. I also want to point out that tornadoes are possible. With this path, the main threat of that will be on the Delmarva. So what else, and better yet, when?
I will answer all of that below... but the path is most important. Considering the map above, the path into the Lower Eastern Shore will bring us primarily a northeast to north wind as it passes. This will affect for how the water piles up or drains around the Chesapeake. That wind direction will likely help to drain (not surge the water like Isabel) , yet push it up against the western bay shores... there will be flooding.
Regardless, water levels will be important. Here are some of the High Tides I was able to
gather for the shoreline areas. The worst part of the storm will be Saturday evening into very early Sunday morning. The Saltwater tides web link below can help you find many more spots and their tides...


Saltwater Tides Link

Models, Rainfall and Flooding

Here is the GFS Model. I have been following this one all week.
The overnight run had the center of Hanna just north of Ocean City at 8pm on Saturday. You will notice the yellow shading over Baltimore that indicated the heaviest rainfall just north and west of the center. Often times these storms will dump more our way than near the center as it interacts with higher terrain and other weather systems.





The Canadian Model also shows 8pm Saturday for the close approach of Hanna.
This position is a little farther south- or just over the southern Chesapeake Bay. If anything, I see the same path, just a slighter slower solution. The time frame here still has us with the worst between 6pm Saturday evening through midnight.






I was looking at the higher resolution NAM model and was concerned with an attempt to slow down or stall Hanna on top of us.
Here you can see the 8pm Saturday evening position near Raleigh/Durham, NC, then reaching us on 8am Sunday. That is a dramatic slow down, and seems to be the only model doing so.
While the cold front to our west is falling apart, the upper level winds will still have enough of a southwesterly push to keep Hanna moving at a brisk pace ranging from15-25mph. This may be using bad data, but I needed to mention it just in case it found something no one else is seeing.
Rainfall
Basically, using the Hydrometeorological Prediction Center maps, here is the forecast for rainfall:
There is a bulls eye (X) over northern New Jersey with 7.99 inches.
Baltimore: 5-6 inches
Westminster: 4-5 inches
Annapolis/Easton: 5-7 inches
Ocean City: less than 4 inches.

All impressive amounts, but should be taken with a grain of salt. There are so many things that can influence rain totals, mainly if and where rain bands set up. We could get a lot more in spots, or a lot less. Either way, the idea goes along with what I mentioned above. The heaviest rain will fall just north and west of the path of Hanna.


Just to recap my forecast:
This evening: Chance of thundershowers.
Tonight: Developing rain/thundershowers. Especially by morning.
Saturday morning: Rain and wind E 10-25mph
Saturday afternoon: Heavy rain, wind E to NE 25-45mph. Temperatures: Mid 70s
Saturday 6pm - Sunday 2am: Heavy rain, water level 1-3 feet higher on the west side of the bay. Wind ranging from 35-65mph Strongest winds on the Bay and Eastern Shore.
Sunday: Clearing, breezy early. Fine for the Raven's game in the afternoon. Partly cloudy to mostly sunny. High 80-85F

Hanna Update: 6pm

Flash Flood Watch and Tropical Storm Watch

This is just a quick update since I am saving my energy for a late night of football. A flood watch has been issued for most of us west of the bay in addition to a Tropical Storm Watch on the water. The NHC plot just updated what I saw at 11am.. models are pulling back a little to the west. That places the center of Hanna between Annapolis and Ocean City mid day or early afternoon Saturday. That also means an east wind for most of the event. While Storm Surge will be limited, the water on the bay may pile more on the western side and raise water levels an extra 1-3 feet in addition to waves. The wind forecast is for 40-60mph, including near Baltimore. Much more tomorrow morning... My full post on similar tracks from this morning is below.

Hanna's Track Shifts Slightly-THIS IS NOT ISABEL

More on Hanna and recent similar storms is posted below. Also, a reminder that this blog is part of my full web site. If you do not see more images at the right here, then click the link above for the full web site.
First, I am thrilled that a lot more of you have taken interest in my blog, but I am amazed how may questions I have gotten about this storm and Isabel. I discussed this earlier in the week- just a few posts back... but I guess I should revisit it again.

THIS IS NOT THE SAME STORM AS ISABEL.

• Isabel reached 150mph winds a few days before landfall-then weakened. The wave memory of that strength is what reached us. Hanna is still a Tropical Storm and only expected to be a minimal Hurricane.

• Isabel tracked to our south and continued inland- pulling steady south east winds up the bay. Hanna should 'turn the corner', and pass off of the coast. It may clip Ocean City, and looks more like the paths of Floyd('99), and...Charley ('04).

I was an expert witness on a case regarding Isabel, and wrote up a 36 page report describing the unique nature of that storm. The 5 year drought, leading into record snow and very wet seasons. The result was water levels raining 2nd and 3rd all time in many spots- before the storm arrived. Then the track of Isabel itself was extremely rare. It passed north of Cape Hatteras, the point on the map that sticks out on the eastern seaboard. Most often, north of there a storm will encounter the mid latitude Westerlies and turn as a result. Isabel passed north of Cape Hatteras, which allowed that high wall of water- the Storm Surge, to pass unimpeded into the Chesapeake Bay. The track never wavered, and continued northwest up towards Toronto. Flooding was from the surge, not the rain. Check out the path and forecast plots here.

High Tide
Flooding in these storms often comes in two forms.

1. Down- Rain from the sky.
2. Up- Storm Surge upon landfall. This is the most destructive.
   

Despite my confidence and attempt to calm the fear of a repeat, people who live along the water will be watching the high tide and timing of the storm for surge flooding. Bowleys Quarters in Baltimore county seemed to get hit the hardest, I thought I would post their High Tides here. The mid day High Tide on Saturday would be the one of most concern. With the expected track and timing now... the following High Tide early Sunday morning should come with a northwest wind, blowing or draining water out the bay.
Tracking Hanna- Why it Shifted East.
Early this week, I was pumping the track from the National Hurricane Center directly over Baltimore. I tried to make it clear that the the range of time and error would likely bring it close, but not directly on that path. For two straight days, the models I look at were consistently plotting Baltimore. Then it began to show a shift to the south and east. Why?
Weather is all about 'teleconnections'. One storm can be impacted by one or a few others. Or even a ridge of High Pressure such as the one that steered Gustav, but gave us clear skies. As Hanna delayed it's development and turn north an extra day, it allowed the remains of Gustav and the Cold Front to our west to get a little closer to us. Carry this to Saturday, and the steering winds are expected to make Hanna turn north then north east before reaching us.
This GFS plot, compared to the last few days, does show a path over Ocean City on Saturday afternoon. That would sift out winds to more of a Northeast to north direction when the storm gets close. The water level in the bay may run high, but also could drop as this happens as the direction of the wind will help 'push' or 'drain' more water out. This could be counteracted by heavy rain, but definitely different than Isabel. Below are the overnight models and National Hurricane Plot for comparison to the last few days in my previous posts. Beyond that is a comparison to recent storms with the same path- Floyd and Charley.
Computer Models- Spaghetti Plot




















Two Storms: Similar Paths, Different Outcomes

While working on a comparison to recent storms with similar tracks, I found two with very different results for Maryland. For starters, it is similar to Floyd, but that was a much stronger storm. At one point, Floyd was on the verge of reaching Category 5 status, and keep pushing from initial threats in central Florida to North Carolina. It was a Tropical Storm when it reach Maryland and passed nearly on top of Ocean City. It was responsible for over 6 inches of rain in Baltimore, 11-13 inches of rain in Annapolis and nearly 20 inches in parts of the Eastern Shore. Ironically, Ocean City had less than 2 inches of rain.Perhaps you remember the images of the town of North East in Cecil County, or Port Deposit at the point where the Susquehanna meets the Chesapeake.















More recently, Hurricane Charley. That came on shore in Florida's Gulf Coast as a Category4, weakened as it crossed into the Atlantic, then hit North Carolina and crossed over Ocean City in a diminished form. By that time, although a similar path to Floyd- no rain fell on the west side of the bay. Quite a contrast.

Hanna Hype, Track To The Right

I hate to skip past our local weather- especially with this late season heat surge, but at least it reminds many that it is still summer, and we have a lot of energy in the atmosphere just waiting to be released.
Here is the GFS model for Saturday morning. It has the center of Hanna just a little closer to the coast, but still very close. Do you remember my right side bias with tropical systems? I have been able to point it out with most storms whit season, except Gustav. Many of these tropical systems have ended up traveling on the right side of that forecast cone. Well, below are the latest tracks for Hanna. You can see a shift to the right side of the track- or to the east. Not much, but still worth noting. While I have pumped up the path crossing Baltimore for the past 2 days, I would have been surprised if that worked out just like that, but I still expect wind and rain Friday night into Saturday. We have to consider a few things:
1. Hanna is just starting to turn this morning. When it does, and the exact angle of acceleration will help determine landfall and beyond.
2. Wind Sheer is relaxing. Hanna has taken a major hit with upper level winds recently, but that relaxes today and allows it to regenerate over warm water.
3. North Atlantic Storm. This Low east of New England actually produced a band of rain in MA that dove south through Long Island. It is producing a band of clouds just to our east this morning. This does need to get out of the way, but could take it's time and deflect Hanna
4. Cold Front from the Great Lakes should help accelerate Hanna and push it out of here in a hurry. These fronts often get here later than expected, and will also determine how Hanna gets turned and spun through the Mid Atlantic. The longer Hanna takes to get here, the closer that front gets, and a better chance to keep Hanna farther east. However, the interaction with the cold front will produce another band of heavy rain and severe storms away from the storm center.

While the Atlantic is now filled with 3 Tropical Storms, let's focus on Hanna maps below. You'll Notice that the National Hurricane Center keeps Hanna as a Tropical Storm when passing us on Saturday.

Hurricane Hanna Heading Here! Tropics Bubbling Up!

Hanna has been upgraded to Hurricane status overnight.
This is the GFM model I mentioned yesterday, still on target with a direct hit from Hanna on Saturday. While the storm be in a diminished form, much like Gustav is today... it will still pose a threat for flooding rain, strong winds, and isolated tornadoes.
While there is a lot of anxiety in this region since Isabel, this will not be the same storm. For starters, it's not nearly as strong, nor projected to get much stronger.
Secondly, the track takes it into South Carolina and brings it up from a longer trip over land. The wind flow may provide some surge of water up the Chesapeake, but both South and North Carolina will take the main hit with water. Check out the tracks below.

First the Spaghetti Plot here shows more models than yesterday bringing this into Maryland. The bulk do have it to our west, but these hurricane models don't handle mid latitude winds that well. The GFS (seen above, and here in red line) does have it much closer to Baltimore.
The National Hurricane Center Forecast Cone considers all models, and perhaps the bias I have mentioned all summer. There is a trend of these storms to ride to the right side of the forecast track... although Gustav did buck the trend. The range of possibilities is wide on Saturday, but below you can see the NHC forecast taking Hanna here Saturday!
As Gustave winds down to Tropical Depression status this morning, it still may dump anywhere from 6 to 20 inches of rain in the deep south. Yet Look at all the activity in the Atlantic below. I think the popcorn might be ready in the microwave.... Ike's track takes it into the Bahamas in TEN may be named Josephine by the end of today.

Models Zero Gustav in on Louisiana

I said last week that I would be amazed if this storm worked out with precision on the LA coastline. In fact, I continued to call for the model bias to far west. Well, I was wrong, here this morning you can see the model agreement slamming just west of New Orleans. This reminds me of the super-storm of '93, when the MRF model was put on the scene with a near perfect forecast 120 hrs (5 Days) out. Sometimes the really big ones don't have to deal with being impacted by other systems to screw things up.
This path would keep the storm surge on the worst case scenario. Lake Pontchartrain and the Mississippi River will take a steady flow from the east and pile up more water than Katrina just based on track alone.

Fluctuation in Strength

Here is the Potential Heat Map showing the warm pool loop north of Cuba, while the depth of the warm water and the temperatures are not as supportive closer to the coast. This is why Katrina weakened just before landfall, and Gustav should do the same. So while it may get back to Cat 4 or maybe just barely a 5, it should break down a little as it reaches land late tomorrow. The bad news is that the 'wave memory' will have a surge resembling the strong version of the storm. This is mush like Isabel did for us. It peaked out at 150mph winds 3-4 days before making landfall, but was beat down to a Category 1/2, with much stronger surge than anyone truly expected up the bay. Consider the forward speed as well, acting like a boat pushing a wake. As of this morning, it was swiftly moving at 16mph, and may speed up. That shortens the time until landfall, and it's chance to weaken much. It also itself increases the wave pressure in front of the storm. so a Category 3 storm moving at 15-20mph may produce a higher surge than a Category 3 moving at 5 mph. In fact you might equate the surge to that of a Category 5- pushing the limits of 25-35 feet of water, similar to what Katrina did to Biloxi, MS.

Tropical Storm Hanna is like the GOP convention. It's still there, but not getting the press coverage it should. We will have to watch this storm, as it may now shift north from the Bahamas to the east coast.
Here is the GFS model showing it at the mouth of the Chesapeake Bay next Saturday. Wouldn't that just stink! I'm supposed to host a Fantasy Football League Party that day!
This is just one of the many potentials, and still 1 week away.
It's good TV, but a horrible set up for too many people. Good luck and G-D speed to the people on the coast.