From the NHC:
SUMMARY OF 100 AM CDT…0600 UTC…INFORMATION
———————————————-
LOCATION…27.5N 88.0W
ABOUT 130 MI…210 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 250 MI…400 KM SE OF MORGAN CITY LOUISIANA
MAXIMUM SUSTAINED WINDS…30 MPH…45 KM/H
PRESENT MOVEMENT…WSW OR 245 DEGREES AT 9 MPH…15 KM/H
MINIMUM CENTRAL PRESSURE…1009 MB…29.80 INCHES
It is pretty amazing how good technology can be sometimes. The GFS knew something, about nine days ago, about PTC-2. I talked about it briefly on the Tropical Update. But here we are, nine days later, and we are waiting for PTC-2 to finally wrap up and get its act together.
Daily dose of science
Potential Tropical Cyclone Two is riding between two ridges and being tugged at by a trough near the Great Lakes. All three of those things are giving meteorologists grey hair trying to figure out which of the three competing factors is going to have the highest impact on PTC-2’s track.
The Tug-of-War continues
The basic premise is that the ridge in the Rockies is getting sliced off on the eastern edge by a mid-level front. That may pull (eventual) Barry north quicker than earlier projections, aided by the ridge to the east.
The animation above shows a brown blotch sliding toward the Gulf across the Mid-South. That is dry air behind a mid-level front. That is cutting off the eastern edge of the big ridge. That eastern edge was the thing that was going to slide (eventual) Barry toward Texas.
That may not be case any longer.
Levi Cowan of Tropical Tidbits (where we get a lot our maps / charts from) did a great explainer in this video:
Forecast model data
The 00z HWRF model data is starting to show the influence of the trough=ridge relationship, too. It shows (eventual) Barry moving WSW and strengthening before putting on the brakes and then shooting north into Louisiana and Mississippi.
And the HWRF tends to do well with tropical systems. It is also one of the first hi-res models to use the new data from the Hurricane Hunters and the extra weather balloon launches at local NWS offices in the Southeast.
I know these images are pretty small, but take a look:
For a zoomed-in look at these images…
First Image
Second Image
Third Image
The HWRF strengthens (eventual) Barry into a Category 1 Hurricane before moving it ashore and it shows very heavy rain falling across parts of Louisiana and Mississippi.
The GFS, a lower-resolution model, agrees with the HWRF on placement, but not on strength.
Science Accomplished! Now to the impacts
Not much has changed with the impacts from our original forecast a few days ago.
Rain
Parts of Louisiana and Mississippi are going to get drenched with about 2 inches to 15 inches of rain. With some spots picking up as much as 20 inches of rain. And there could be some places that get even more, depending on how the feeder bands set up.
I know 2 inches to 15 inches is a pretty wide spread, but across the region, that is going to be the spread.
Model guidance is showing the potential for even more rainfall in some places. And I anticipate the WPC may increase the rainfall forecast given some of the newer data.
Here is another look at the list of places from yesterday with update rainfall estimates based on model guidance, and not the official forecast from the WPC:
Louisiana
New Orleans – 10+ inches
Baton Rouge – 10+ inches
Lafayette – 8+ inches
Alexandria – 5+ inches
Lake Charles – 3+ inches
Shreveport – 2+ inches
Mississippi
Gulfport – 10+ inches
Hattiesburg – 7+ inches
McComb – 6+ inches
Jackson – 5+ inches
Meridian – 6+ inches
Tupelo – 2+ inches
Wind
Hurricane-force wind won’t be as much of a concern inland. Instead, Tropical Storm-force wind will be the concern for inland areas of Louisiana and Mississippi.
The NHC forecast is for (eventual) Barry to strengthen to a hurricane with winds around 80mph, but those winds will only be felt along the immediate coastline within 20 to 30 miles of landfall – if not even closer. Everywhere else can anticipate weaker wind. And the further inland you travel, the weaker the wind will be.
Given how slow the storm is currently moving and the forecast form the NHC as well as model trends… if you live 50 miles inland from the coast, you can anticipate your sustained wind speed to be cut in half from the observations on the coast. Live 190 miles inland? take off another half from that.
So a Category 1 Hurricane on the coast with 80mph wind will only produce a 40mph sustained wind 50 miles inland. At 100 miles inland? A 20mph sustained wind. Now, keep in mind, wind gusts can reach up to 20mph higher than the sustained wind speed with this system.
Surge
I don;t often talk about surge with my coverage area being so far inland, but in this case I wanted to touch on it quickly.
This is the inundation map from the NHC that shows some areas along I-10 in Mississippi NE of Slidell under -up to – three feet of water. Not from rain, but from storm surge.
This is what the NHC warns:
The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…
Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.
Forecast: Mouth of the Pearl River to Intracoastal City…3 to 6 ft
Timeline
This is a very slow moving system that is trapped between three different amtospheric features. It isn’t going to be in a hurry to do anything – move or strengthen.
Storm timeline
Thursday – Likely a Tropical Depression while organizing itself further and strengthening south of the Louisiana/Mississippi border in the Gulf, moving west
Friday – Possibly a Tropical Storm, at least a Tropical Depression given latest model data south of Thibodaux, Louisiana moving northwest approaching land
Saturday – Likely Tropical Storm or weak Hurricane, making landfall somewhere between Lake Charles, Louisiana and New Orleans, Louisiana, during the mid-day hours, moving north
Sunday – Inland
Impacts Timeline for South of I-20
Thursday – Showers and storms in Louisiana, Mississippi and Alabama loosely associated with (eventual) Barry
Friday – Storms in Louisiana, Mississippi and Alabama associated with (eventual) Barry, some flooding possible along the coast withing 40 miles of the Gulf across parts of Louisiana and Mississippi
Saturday – Heavy rain in Louisiana and Mississippi associated with (eventual) Barry, flooding possible, downed trees possible, power outages possible, tornadoes also possible
Sunday – Heavy rain in Louisiana and Mississippi associated with (eventual) Barry, flooding possible, downed trees possible, power outages possible, tornadoes also possible
How can I prepare now, Nick?
If you live in a flood-prone area, assess your surroundings. Is the creek near your house clear of debris? Are the storm drains clogged? Fix those things now. If a Flash Flood Emergency was issued for your area, do you know where to go? Find a safe place from flooding now.
Don’t feel safe in your home during bad weather? Reach out to a friend! Go hang out at their place this weekend.
While this isn’t anticipated to be some Monster Hurricane, prolonged rain can cause serious problems. Flooding is the deadliest form of severe weather. It kills more people than tornadoes. So please take it seriously.
Also check your Hurricane Preparedness Kit. That’s about it. Make sure you have enough supplies to last a few days without power and water. Not because this system is anticipated to wipe out power and water to an area, but rather, you should always have enough supplies to last a few days without power and water during Hurricane season.
